Category: Interview Questions

1. Explain The Access Control Policy?what Is The Purpose Of Access Control Policy?

There are two types of access control, both of which are policy-based: command-level access control and resource-level access control.

Command-level access control determines whether the user is allowed to execute the particular command within the store you have specified. 

Resource-level access control policy could be applied to determine if the user can access the resource in question. 

Access control in a WebSphere Commerce application is composed of the following elements: users, actions, resources, and relationships.

Users are the people that use the system. For access control purposes, users must be grouped into relevant access groups. 

Actions are the activities that users can perform on the resource. For access control purposes, actions must also be grouped into relevant action groups. For example, a common action used in a store is a view. A view is invoked to display a store page to customers. The views used in your store must be declared as actions and assigned to an action group before they can be accessed. 

Resources are the entities that are protected. For example, if the action is a view, the resource to be protected is the command that invoked the view, for example com.ibm.commerce.command.ViewCommand. 

Relationships are the relationship between the user and the resource. Access control policies may require that a relationship between the user and the resource be satisfied. For example, users may only be allowed to display the orders that they have created.

2. Explain The Dynacache?

1. Now a days the requirement is changed that caching should be implemented for the content that changes frequently.
2. The bright solution for this is DynaCache system which is provided by IBM Websphere Application server.
3. Dyna Cache is to be configured to catch some objects and later based on some matching rules Dyna cache retrive those objects from the cache.
4. Caching rules are specified in Cachespec.xml file.

3. What The Ejb Transaction Parameters?

Possible values for TRANSATTRIBUTE are:

NotSupported
:Bean cannot be involved in a transaction. If the client has started a transaction, the existing transaction is suspended until the bean’s method has completed.

Required :
Bean must always run within a transaction

Supports
:If the client has started a transaction, the bean joins the transaction.

RequiresNew
:Bean always starts a new transaction.

Mandatory:
The client must start a transaction when the bean is invoked.

Never
:If the client has started a transaction, the bean throws an exception. 

4. Which Are Different Types Of Entity Beans N Which One Is Used In Commerce?

There are 2 types of entity beans available namely

• BMP-Bean Managed Persistence
• CMP -Container Managed Persistence

CMP is used in commerce to interact with the database in commerce.

5. Which Are The Different Types Of Databeans. What Is Commonly Used In Commerce.when Do We Use It?

A data bean is a Java bean that is used within a JSP page to provide dynamic content. A data bean normally provides a simple representation of a WebSphere Commerce entity bean.

There are two types of data beans: smart data beans and command data beans.

 A smart data bean uses a lazy fetch method to retrieve its own data. This type of data bean can provide better performance in situations where not all data from the access bean is required, since it retrieves data only as required. Smart data beans that require access to the database should extend from the access bean for the corresponding entity bean and implement thecom.ibm.commerce.SmartDataBean interface. When database access is not required, the smart data bean should extend the SmartDataBeanImpl class.

A command data bean relies on a command to retrieve its data and is a more lightweight data bean. The command retrieves all attributes for the data bean at once, regardless of whether the JSP page requires them. As a result, for JSP pages that use only a selection of attributes from the data bean, a command data bean may be costly in terms of performance time. Command data beans can also extend from their corresponding access beans and implement thecom.ibm.commerce.CommandDataBean interface.

SmartDataBean is commonly used in wcs.We use command databean only when using Command databean is impractical.

6. Which Are The Different Flavours Of Ejb In Wcs ?

Different flavours of EJB available in WCS are Session Bean and Entity Bean. 

7. What Are Acessbeans? What Is The Advantage Of Accessbean?

WebSphere Commerce commands interact with access beans rather than directly with entity beans. Access beans provide a simpler interface to clients, caching of the home object, and reduced call traffic to the enterprise bean.Access beans behave like Java beans, and hide all enterprise bean-specific programming interfaces from the client, like the JNDI, home and remote interfaces.

Advantage of accessbean:

 At run time the access bean caches the enterprise bean home object because look ups to the home object are expensive, in terms of time and resource usage.

The access bean implements a copyHelper object that reduces the number of calls to the enterprise bean when commands get and set enterprise bean attributes. Only a single call to the enterprise bean is required when reading or writing multiple enterprise bean attributes. 

8. State One Diff Between 6.0 And 7.0 Commerce Version?

Social Commerce Support,Coshoping provision, rich look and feel,starter stores optimized for mobile devices. 

9. What Is Optimistic Locking?

WebSphere Commerce uses an optimistic locking scheme that allows the database transaction isolation level to be lowered from repeatable read to read committed. Using that scheme, database rows not normally accessed concurrently are not locked with an intent to update when they are read. Instead, when the update is eventually made, the row is checked to make sure it has not been updated concurrently since it was read. If it has been updated concurrently, then the transaction is rolled back and the command may be restarted from the beginning in a new transaction, if appropriate. In this scheme, performance is improved when concurrent updates do not normally occur, because the relatively expensive process of obtaining the database locks with intent to update is avoided.

On the other hand, for those operations where concurrent updates are more likely to occur, pessimistic locking, whereby intent to update locks are obtained when the row is read, continues to be used, thus avoiding the more expensive process of rolling back and re-starting from the beginning in a new transaction. 

10. Which Are The Different Subsystems In Commerce?

There are mainly 6 subsystems available in WCS namely:

1. Catalog.
2. Member.
3. Order.
4. Marketing. 
5. Merchandising.
6. Trading.

11. How To Know Whether An Inventory Is Allocated For The Order Or Not?

By checking in to OrderItems table InventoryStatus column.If that column has an value as allc then an inventory is allocated for the order.

12. How Many Types Of Inventory Exists?

There are 4 types of inventory exists in wcs namely:

1. ATP  
2. Non ATP
3. External Inventory
4. No Inventory.

13. What Are The Different Types Of Order Capture?

WebSphere Commerce supports several mechanisms for submitting orders.

A customer or Customer Service Representative can submit an order using any of the following methods:

• Requisition lists 
• Wish lists 
• Shopping carts 
• Scheduled orders are recurring orders 
• Quick orders 
• Copied orders 
• Sales quotes.

14. How Many Ways Calcode Can Be Attached?

3 ways calcode can be attached :

1. Direct attachment:
   Here, we can attach a calcode to order or orderitem directly
2. Indirect attachment:
   Here, we attach a calcode to catalog or catalog group. Hence, every item in a particular catalog or catalog group is indirectly attached to calcode that is attached to that catalog or catalog group.
3. Default attachment:
   Here, we implicitly attach a calcode specifying a calcode to an orderitem in STENCALUSG table.

15. When Taxes Are Calculated?

Taxes are calculated when we proceed to checkout.

16. What Are Calmethods?

Calculation methods use the information that is part of calculation usages, calculation codes, and calculation scales to determine monetary amounts for order items. Calculation methods are categorized by the task that they perform within the calculation framework and the part of the calculation framework to which the calculation method belongs.

17. What Is Fulfilment Center?

Stores use fulfillment centers as both inventory warehouses and shipping and receiving centers. One store can have one or many fulfillment centers.

18. What Is Calcode?

While attachment is defined outside of a calculation code, the following properties are defined as part of a calculation code:

• A calculation usage. This specifies the calculation type for which a calculation code can be used. Calculation usages are covered in Calculation usages.
• Calculation methods that are used to qualify, calculate, and apply the calculation code.
• A flag indicating if a calculation code must be qualified or not.
• A flag indicating if the calculation code is active, inactive, or marked for deletion.
• The method of grouping order items for calculations.
• A sequence number that is used to determine the order of calculations when multiple calculation codes of the same calculation usage apply to an order item.
• A time range during which the calculation code is in effect.
• These properties are defined in the CALCODE database table. 

19. Different Types Of Charges?

There are 7 types of charges, those are:

• discount
• shipping
• sales tax
• shipping tax
• coupon
• surcharge
• shipping adjustment

20. What Is Calculation Usage?

Calculation usage consists of types of taxes that can be attached to an order item.
By default we have 7 types of taxes like shipping, discount, shipping tax, etc.
All those can be found in CALUSAGE database table.

21. Difference Between Static Kit And Packages?

Packages:
A package is an atomic collection of catalog entries. It is that all the items in a package can sold together but individual selling of items in a package is not allowed.

Static Kits:

1. A static kit is a group of products that are ordered as a unit.
2. A static kit will back order if any of its components are unavailable.
3. A static kit is first created as a package then configured by an administrator.

22. What Is Attribute Dictionary?

An attribute dictionary is a set of common attributes and attribute values that can be reused by multiple products. The attribute management tool in Management Center provides business users the ability to create,update, assign, and manage product attributes.

23. What Is The Difference Between Product And Item?

Products: A product acts as template for a group of items(or SKUs) that exhibits the same attributes.

Items: An item is a tangible unit of merchandise that has a specific name, part number and price.

24. Which Tool Is Used For Catalog Management ?

Product Management Tool.

25. Explain The Sku,partnumber?

Every product has a unique identification number when it is Manufactured i.e.,PartNumber.SKU is a store keeping unit which is a number when a products  are orderable.

26. Difference Between Mastercatalog And Sales Catalog?

There are two types of catalogs in a WebSphere Commerce system: master and sales. While a master catalog is the central location to manage all your store’s merchandise and services, a sales catalog is a subset of the merchandise and services found in the master catalog.

      Every store in the WebSphere Commerce system must have a master catalog. Only one master catalog can exist at a time, and multiple stores can share a master catalog. However, you can create one or more sales catalogs for customer display purposes. A sales catalog has a flexible display structure that allows you to associate products to more than one category, to suit the requirements of your store. 

27. How Can We Make A Command Retriable?

A retriable command is a controller command that can re-execute itself after encountering a system-level exception during the command execution.

To make an existing controller command retriable, must perform one of the following steps:

Set the retriable properties in the PROPERTIES column of the CMDREG database table, where PROPERTIES is the default properties associated with this command. The properties are in the property1=value1&property2=value2 form, where propertyn is the name of the property and valuen is the value corresponding to the property.

Set an instance property in the wc-server.xml file.

Functional architecture and Runtime architecture of WCS 6.0/WCS 7.0.

28. Which Exception Is Retriable?

ECSystemException.

29. Which Are Different Types Of Exceptions Used In Commerce?

ECApplicationException : 
This exception is thrown if the error is related to user input and will always fail. For example, when a user enters an invalid parameter, an ECApplicationException is thrown. When this exception is thrown, the solution controller does not retry the command, even if it is specified as a retriable command.

ECSystemException : 
This exception is thrown if a runtime exception or a WebSphere Commerce configuration error is detected. Examples of this type of exception include create exceptions, remote exceptions, and other EJB exceptions. When this type of exception is thrown, the solution controller retries the command if the command is retriable and the exception was caused by either a database deadlock or database rollback. 

30. List The Different Business Models Of Wcs?

The different business models of wcs are:

1. B2C 
2. B2B 
3. Demand chain 
4. Supply chain
5. Value chain and
6. Extended sites.

31. What Does Map.mapxmi File Contain?

Mappings from EJB bean attribute definitions to database table schema column definitions .

32. What Is The Use Of Commitcopyhelper() And Refreshcopyhelper()?

commitCopyHelper():
Instead of using the remote interface, CopyHelper Access Beans exist that contain getters and setters for CMP fields that do not exist on the remote interface. The methods within the CopyHelper Access Beans write data to a hash table that in turn updates the database when commitCopyHelper() is called. The hash table can record multiple database changes then update the database in one transaction, unlike the remote methods which require one transaction per change.

RefreshCopyHelper():
which does the reverse function of commitCopyHelper(). The method refreshCopyHelper() writes to the hash table from the database.

33. Why Is Struts-config Entry Required While Creating A Jsp Or A Command?

To map views to corresponding JSP pages .

1. What Is Bluetooth?

• Bluetooth is a wireless technology standard used to exchange data over short distances.
• The data is exchanged from fixed and mobile devices by creating Personal Area Network with security at high level. 
• Bluetooth was originally conceived as a wireless alternate to RS-232 cables. 
• It resolves the problems synchronization by connecting several devices. 
• It requires a low-cost transceiver chip that needs to be included in all the devices.
• The connections can be point to point or multipoint.
• A built in verification and encryption is also provided.

2. Bluetooth Is Called A Cable Replacement Technology. Explain.

• Bluetooth allows Personal Area Networks without the cables.
• It provides connectivity to many mobiles users at a time for sharing without wires. 
• Bluetooth chip is designed for replacing cables by transmitting the information at a special frequency from sender to receiver. 
• Bluetooth is an inexpensive,low-power, short range radio based technology.
• Cabling involves a lot of cost foe execution.
• Bluetooth is much more flexible and robust than cabling.
• They even require a very low bandwidth of data transfer.

3. Explain About Tcp Flow Control?

TCP utilizes a flow control protocol from one end to another end for avoiding the sender to send data too quickly for the TCP receiver to receive and process it in a reliable manner. Machines of diverse network can communicate quickly by having the flow control mechanism.

TCP utilizes a sliding window flow control protocol. In every TCP segment, the receiver is specified in a receive window field, the additional received data that is to buffer for the connection. When a window of size 0 is advertised by a receiver, the data sending is stopped by the sender and starts the persist timer. The TCP dead lock situation is protected by the persist timer. The TCP sender sends the packet and the receiver sends the acknowledgement with the new size of window, at the time of expiring the persist timer.

4. Explain The Working Of Trace Route?

Trace route works by increasing the time-to-live value of every successive packets sent in batch. Every three packets that were sent first, have a time-to-live value 1. The next three packets have a TTL value of 2 and so on. The host decrements the TTL value by one and the packet is forwarded to the next host, when a packet passes through a host.

When a packet (with a time-to-live value of 1) reaches a host, the packets will be discarded by the host, and an ICMP time exceeded packet is sent to the sender. A list of hosts, whose packets have traversed enrouted to the destination, is utilized by the trace route utility.

5. What Is Piconet?

Piconet is an ad-hoc network by linking a group of users which uses blue tooth technology protocols for allowing one ‘master’ device to interconnect with up to seven active ‘slave’ devices. Further, up to 255 slave devices could be inactive or packed and the master device can bring into active status at any given point of time.

The range of Piconet will vary based on the blue tooth device class. The data transfer rate varies around 200 to 2100 KB/S, depending upon the synchronous or asynchronous connection usage, and the number of devices connected in the piconet.

6. Explain The Following Terms: Icmp, Arp, Multicast, Broadcast

• Internet Control Message Protocol:
  This protocol is used for while checking the connectivity using ping command
• Address Resolution Protocol:
  This protocol is used to know about the properties of TCP/IP. For example, to know other system MAC addresses.
• Multicast:
  Communication between single sender and a list of select recipients in a network.
• Broadcast:
  To send messages to all the recipients simultaneously in a network.

7. List Out The Differences Between Udp And Tcp?

• TCP is connection oriented protocol, where as UDP is connection less protocol.
• In TCP, information is sent after establishing the connection from client to server, where as data is sent in chunks in UDP.
• TCP is reliable – unless the connection fails completely, the message will be reached to the destination.
• UDP is unreliable – there are chances to lose the data sent on the way.
• TCP is an ordered protocol – when messages are sent one after other, the first message will be received first.
• UDP is an unordered protocol – when two messages are sent, the order of their arrival at the destination is unknown.

8. What Is Meant By The Term ‘ip Spoofing’?

IP Spoofing
: Sending messages by intruder to a computer system with an IP address that indicates the message is sent from a trusted host, for gaining unauthorized access to computer systems. The hacker / intruder first utilize a variety of techniques for finding an IP address of a trusted host. Later he modifies the packet headers, in order to give an illusion that the packets are sent from the host.

9. What Is Rj-45?

• RJ-45 stands for Registered Jack – 45.
• It is an 8-wire connector for connecting computer systems on to a LAN, especially Ethernets.
• These connections are similar in appearance to the ubiquitous RJ-11, which are used in connecting telephone equipment, with little more width. 
• It is one of the most commonly used connectors.
• Two wiring schemes like T568A and T568B are used to terminate the twisted-pair cable to the connector interface.
• They look similar to the RJ-11 connectors which are used for connecting the telephone equipments but are wider then them.

10. Which Technology Is Used To Avoid Interference In Bluetooth?

Blue tooth uses frequency hopping technology. In this technology, 79 hop frequencies are transmitted and received from 2402 to 2480 mhz. hopping in a pseudo random sequence at a rate of 1600 times in a second. Guassian frequency shift keying modulation is utilized with a maximum data transfer rate of 721 kbps. Bluetooth protocol stack is developed and TCP/IP imported layers are used in this technology.

Interference is being avoided by utilizing the frequency-hop(FH) spread spectrum technology. It is adaptable for low-power, low-cost radio implementations and also used in certain wireless LAN products.

The major advantage with this technology transmission is the high rate of 1600 hops / ps. Another advantage is, short packet length is also used by Bluetooth.

11. What Is Tcp Connection Establishment And Tear Down?

The following is the process for TCP connection:

• As connection is made by synchronizing sender and receiver and the OS is informed about the connection establishment.
• Sender starts sending information and gets acknowledged. Soon after the sender sends the data, a timer is started.
• When the sender is not received any acknowledgement ever after exceeding the timer’s limit, the data is transmitted.
• If windowing occurs, buffer on the receiver is full, then a stop signal is sent by the sender and stops sending information.
• Soon after processing all data, a go signal is sent by the sender, followed by transmitting data again.

12. What Is The Signal Strength Transmitted By Cell Phones?

The magnitude of the electric field at a reference point, which is significant distance from the transmitting antenna, is known as signal strength. Signal strength is expressed in voltage/length or signal power received by the antenna. In mobile phones, the signal strength is usually expressed in dB-microvolts per meter or in decibels above a reference level of one milliwatt.

13. What Method Is Used For Voice Transfer? Brief About The Method Used?

For Voice transfer, SCO (Synchronous Connection Oriented) links are used for good synchronization and reliability.

14. Explain The Modulation Techniques Used In Bluetooth Technology?

Blue tooth uses Frequency Hopping Spread Spectrum technique which is used in spread spectrum signal transmission. During radio transmission, frequencies are switched repeatedly, to help reducing unlawful access to cross paths which causes interruptions. FHSS makes Bluetooth communication more robust and secure. The speed of interferences from other devices will be reduced, though it will not cause the transmission to stop. 
Adaptive modulation and coding methods, OFDM, GMSK, QAM, CDMA, DMT and similar methods are utilized in the areas of wireless, cellular and satellite communication systems. These modulations are used in wireless, cellular, wired line and satellite communication systems.

New technologies such as MIMO, BLAST and space-time coding are used in transmission data communication systems.

15. What Are The Technical Characteristics Of Bluetooth?

The following are the technical characters of a Bluetooth device:

The devices are either a one chip solution or multiple chips in general. Blue tooth device has three main parts – RF, baseband processor and link manager (could be a CPU core like 8 or 16 bit Reduced Instruction Set Computer. A BT module in multiple chips, usually 2 or 3 chip, like RF on a chip are produced by certain vendors.

For a single chip solution, the following information can be used for referencing from a particular vendor.

• Package
  :  81 ball BGA, 8mm x 8mm
• Supply Voltage
  : 2.7 – 3.3v
• Power Consumption
  : Data transmitting @ 4dBm – type 41mA
• Voice Only Connection
  : 15mA for HV3 packets, 30mA for HV1
• RI Page Scanning :
   420uA
• Inquiry Scanning + RI Page Scanning
  : 560uA
• Park mode (1 second interval)  : 
  120uA
• Standby state  
  : 10uA

The components, the chip, memory and the crystal, antenna could be placed on a PCB about 20mm x 15mm. The thickness of the chip is about 1.25mm or 1.55 mm..

16. Explain The Term ‘airport’ In Bluetooth?

Airport is standard (802.11) and has a faster transfer rate. Technologically it is more advanced, more rugged and smaller and capable of being used anywhere. It is 10mb/sec, 50 meters, 10 active devices. Apparently, Bluetooth is 1mb/sec, 10 meters and 7 active devices.

17. What Does Fec Mean In Bluetooth?

• FEC stands for Forward Error Correction. On the data payload, FEC reducing the number of retransmissions.
• Within blue tooth, there are 2 versions namely, 1/3 FEC and 2/3 FEC. 
• The 1/3 version is 3 times repetition of each information bit. 
• The 2/3 version is a shortened Hamming code. 
• It is known as a method of obtaining error control in data transmission in which the source sends redundant data and the destination will recognize it without the errors.
• They are used for broadcasting to many destinations from a single source.

18. How Frequency Hopping Is Used For Security In Bluetooth?

Blue tooth technology uses Adaptive Frequency Hopping and capable to reduce interference between wireless technologies with the help of 2.4 GHz spectrum. In order to take the advantage of the available frequency, Blue tooth’s AFH works within the spectrum and is performed by the technology detecting other devices in the spectrum and avoiding the used frequencies. Efficient transmission within the spectrum at high degree of interference immunity is achieved by adapting hopping among 79 frequencies at 1 MHz intervals.

19. What Is 3g?

Definition: 3G, known as 3rd Generation, is a standard for mobile / cellular phones. It provides the services that fulfill the International Telecommunication Union specifications.

The application services of 3G include wireless voice telephone, mobile internet access, video calls and mobile television – all in a mobile environment.

• 3G allows simultaneous use of speech and data services
• 3G provides peak data rates of at least 200 KBits according to the IMT-2000 specification.
• Mobile broadband access of several MBits to laptop computer systems, smart phones is provided by latest 3.5G, 3.75G versions.

20. What Are 3g Standards?

3G standards:

UMTS:

• Universal Mobile Telecommunications System – One of the 3G mobile telecommunications technologies, also being developed into a 4G technology.
• Most common form of UMTS uses W-CDMA as an underlying air interface.
• UMTS also covers Radio Access Network – UMTS Terrestrial Radio Access Network (UTRAN), and Mobile Application Part (MAP).
• Users are authenticated via USIM cards (Universal Subscriber Identity Module).

CDMA2000

• Also known as IMT Multi-Carrier (IMT-MC), uses CDMA channel access for sending voice, data and signaling data between mobile phones and cell sites.
• The standards are CDMA2000 IX, CDMA2000 EV-DOR Rev.0, CDMA2000 EV-DO Rev.A and CDMA2000 EV-Rev.B. They are approved radio interfaces for the ITU’s IMT-2000.

21. What Are The Advantages And Disadvantages Of 3g?

Advantages of 3G:

• Overcrowding is relieved in existing systems with radio spectrum
• Bandwidth, security and reliability are more
• Provides interoperability among service providers
• Availability of fixed and variable rates
• Support to devices with backward compatibility with existing networks
• Always online devices – 3G uses IP connectivity which is packet based
• Rich multi media services are available

Disadvantages of 3G:

• The cost of cellular infrastructure , upgrading base stations is very high
• Needs different handsets.
• Roaming and data/voice work together has not yet been implemented
• Power consumption is high
• Requires closer base stations and are expensive
• Spectrum-license costs, network deployment costs and handset subsidies subscribers are tremendous.

22. How Is 3g Different From 2g?

• Packet data speed is higher in 3G, and it is up to 384 KBPS
• Voice and sms speed is also 384 KBPS in 3G
• 2G utilizes different switching techniques for voice and data, where as 3G uses single switching, irrespective of data
• 3G has at least 2MB of data link of a mobile, where in 2G the data rate is in KBPS
• 3G has WiMAX facility for faster VOIP and internet
• 2G uses GSM TDMA technology with narrowband 200Khz.
• 3G uses CDMA technology with broadband 5Mhz, with same frequency carrier and time.

23. Explain Gprs ( General Packet Radio Service)?

GPRS ( General Packet Radio Service) : 

• Packet oriented mobile data service available to the users of 2G cellular systems.
• It is global system for communicating through mobile phones using GSM as well as in 3G systems.
• GPRS data transfer is charged per MB of traffic transferred, where as in circuit switching, data transfer is charged per minute of connection time
• GPRS is better packet switching service, as opposed to circuit switching.
• 2G cellular systems are combined with GPRS and known as 2.5G.
• Provides moderate speed data transfer by using unused TDMA channels, such as GSM.

24. Explain Gsm (global System For Mobile Communications)?

GSM (Global System for Mobile Communications):

• GSM (Global System for Mobile Communications).
• Most popular standard for mobile telephony systems, originated from Groupe Special Mobile.
• The ubiquity of GSM enables the international roaming arrangements among mobile phone operators.
• Both signaling and speech channels are digital, and thus GSM is considered as 2G mobile phone system.
• GSM standard benefited customers the ability to roam and switch carriers without replacing the hand sets and network operators.
• GSM implements low-cost implementation of Short Message Service.

25. Explain Hlr (home Location Register) , Iden(integrated Digital Enhanced Network), I-appli ?

HLR (Home Location Register) :

• For GSM and CDMA wireless networks
• It’s responsibility is to authenticate and authorize subscribers and their services.

iDEN (Integrated Digital Enhanced Network) : 

• A wireless technology for Motorola
• It has the capabilities of digi-cellular phone, 2 way radio, alphanumeric pager and data modem / fax modem in a single network
• Operational bands are 800 MHz, 900 MHz and 1.5 GHz
• iDEN is based on TDMA (Time Division Multiple Access) and GSM architecture
• For voice compression it uses Motorola’s Vector Sum Excited Linear Predictors vocoder.
• For delivering 64KBPS over a 25 KHz channel, it uses QAM modulation.
• iDEN is designed to serve the mobile user for accessing information quickly without carrying several devices.

i-appli : 

• i-appli is a Java environment based on CLDC.
• Handsets of NTT DoCoMos are utilizing i-appli
• It is similar to MIDP, however both APIs are incompatible.

26. Explain Umts?

• UMTS stands for Universal Mobile Telecommunications Systems
• One of the emerging mobile technologies for 3G mobile phones.
• The main benefit of UMTS is, undoubtedly, its speed
• Current rates of broadband data transfer is 2MBits / second
• The speed of UMTS makes it possible to stream video that supports movie downloads and video conferencing.
• In a nut shell, UMTS provides almost all the facilities of a home computer system while on the move.
• UMTS combines the technologies like wireless, satellite which provides seamless transitions between Wi-Fi and satellite.

27. What Is 4g?

• A short name for Fourth Generation
• A stage of broadband mobile communications that supersede 3G
• 4G is expected to use radio spectrum in an efficient manner, and as a result, provides cable-modem transmission speeds to the end users.
• This feature enables high-quality streaming video
• Simultaneous connections to multiple high-speed networks, known as pervasive computing, are expected by 4G.
• Thus seamless handoffs are provided throughout a geographical area.
• Coverage enhancement technologies, like femtocell and picocell are expected to develop for addressing various needs of mobile users in homes, public buildings etc.

28. What Is International Telecommunications Union And What Are Its Functions?

• ITU is an intergovernmental organization
• Telecommunications are developed by using ITU by public and private organizations.
• ITU is responsible for adopting regulations, international treaties and standards that governs telecommunications

Functions of International Telecommunications Union:

• Maintaining and extending the international cooperation for the improvement
• Rational usage of telecommunications, for promoting efficient use of technical facilities
• To harmonize the actions of nations.

29. What Is Cdma2000?

• CDMA2000 is a Multi-carrier code-division multiple access version of IMT-2000 standard
• CDMA2000 is a 3G wireless technology.
• World’s first 3G commercial system was launched by SK Telecom of South Korea using CDMA2000 1X
• CDMA 2000 supports mobile data communications at speeds from 144KBPS to 3MBPS
• The versions of CDMA2000 have been developed by Qualcomm and Ericsson
• There were 250,300,000 subscribes world for CDMA by March 2006.

30. What Is Cdma? Explain The Technology.

• CDMA stands for Code Division Multiple Access
• CDMA is a wireless technology used in transmission of signal from places with high Security and noise reduction.
• The principle of Spread Spectrum is used to work with CDMA.
• Spread signal is below the noise level noise and has no effect on the signal.
• CDMA does not frequency specific to each user. Instead, every channel uses the full available spectrum.
• Individual conversations are encoded with a pseudo-random digital sequence.
• CDMA always provides better capacity for voice and data communications
• CDMA is a common platform for 3G technologies
• Analog radio transmission technologies like Advanced Mobile Phone System were used in CDMA at the time of its inception
• A unique code is received by all mobile network users and is allowed continuous network access instead of intermittent and timed access.

31. Explain Cdma One And Cdma2000?

CDMA One : 

• CDMA one refers original ITU IS-95 CDMA wireless interface protocol. It is considered as a 2G mobile wireless technology
• The version IS-95A protocol employs a 1.25 Mhz carrier and data speeds up to 14.4 Kbps
• The version IS-95B support data speeds up to 115 kbps by employing 800 MHz / 1.9 GHz.

CDMA2000 :

• Also known as IMT Multi-Carrier, a family of 3G mobile technology standards.
• Used for sending voice, data and signaling between cell sites and mobile pones
• The standards such as CDMA2000 1X, CDMA2000 EV-DO Rev. 0, are approved radio interfaces for ITU IMT-2000
• CDMA 2000 is backward compatible with its previous 2G iteration IS-95

32. Explain Edge?

• EDGE is an acronym for Enhanced Data GSM Environment
• An improved wireless technology over GSM
• A 2nd generation cell phone technology
• EDGE is used for wireless data transfer via mobile phone connection
• Data transfer rates up to 4 times more than GSM networks
• With the advent of Blackberry and iPhone, faster data transfer is sought
• Using more sophisticated coding, usually without high end hardware, wireless carrier’s base stations are supported for data transfer speeds up to 384 KBPS
• EDGE is an alternative to replacing wireless technology, such as GPRS
• EDGE will eventually be replaced by 3G technology such as WCDMA.

33. Explain Dect?

• DECT is one of the wireless technologies, originated in Europe
• DECT was designed to interwork with various networks such as PSTN, ISDN, GSM etc.
• The initial standard. of DECT focused on developing air interface which is a radio link between cordless telephone and the base stations
• This standard plugged into the telephone socket and the standard protocols for handover between several base stations
• All these are connected to the same office switchboard, typically a PABX
• The first product of its kind was from Olivetti, was a wireless LAN type product, known as NET3.

34. Explain High Speed Packet Access?

• HSPA is a combination of 2 mobile telephony protocols – High Speed Downlink Packet Access and High Speed Uplink Packet Access
• HSPA improves the performance of existing WCDMA protocols.
• HSPA provide increased performance by utilizing schemes of modulation and refining the protocols, through which the base stations and handsets communicate
• HSPA is used for better usage of the available bandwidth provided by WCDMA
• HSPA supports data rates of up to 14 MBit / s in the downlink
• HSPA supports data rates of up to 5.8 MBit / s in the uplink
• HSPA reduces the latency and increases up to 5 times more system capacity during downlink and twice more system capacity during uplink
• HSPA uses 16QAM for yielding higher bit rates
• HSPA rollouts are achieved by implementing software upgrades to existing 3G networks. This gives HSPA a head start over WiMax.

35. Explain Ev-do/ Evdo?

• EVDO stands for Evolution Data Optimized
• EVDO is a 3G broadband technology used by Verizon, Spring, Alltel
• It provides typical download speeds of 600 to 1400 KBPS
• A personal broadband service for wide range of customers
• It is always On
• EVDO utilizes CDMA signals
• Users can be connected remotely for using email, downloading large files, spreadsheets etc.
• EVDO is relatively low cost with high capacity
• Allows rich web browsing and application usage
• Seamless roaming, internal internet connectivity without relying on other’s connection, accessibility to the corporate Virtual Private Network by customers are some of the advantages over WiFi.

36. What Is The Difference Between Cdma And Gsm?

The important differences are:

Data Transfer Speed:

• CDMA is faster than GSM.
• CDMA2000 downstream rate is 2 megabits / second, through EVDO, where GSM downstream rate is up to 384 kilobits / second, through EDGE technology

Subscriber Identity Module (SIM) cards:

• SIM is tied to the network, rather than the actual phone. Phones with card-enabled can be used with any carrier of GSM
• Proprietary handsets are linked to one carrier only and not card-enabled in CDMA

Roaming:

•  GSM carriers have wider coverage of more rural areas, where as CDMA may not cover rural areas compared to GSM carriers

International Roaming:

• GSM has facility to offer more international roaming, as the number of connections in world market dominate GSM network.
• CDMA phones do not have the capacity; however, there are more countries that use CDMA networks.

37. What Is The Importance Of Cdma In Today’s Cellular World?

• The transition to digital radio through the process of defining standards is implementing about 90% in the cellular industry.
• Smooth transition to digital standards is involved in CDMA technology.
• Most often, it can be viewed as improved and replacement technology of TDMA
• Moving towards 4G technology is compatible with CDMA technology.

38. What Is The Differentiate Between Cdma And Fdma ?

CDMA and FDMA 

CDMA : 

• Same frequency is used by every user and simultaneous transmission occurs
• Every narrowband signal is multiplied by wideband spreading signal, usually known as codeword
• Every user has a separate pseudo-codeword, i.e., orthogonal to others
• Only the desired codeword is detected by the receivers and others appear as noise
• It is mandatory for the receivers to know about the transmitter’s codeword

FDMA :

• When the channel is not in use, it sits simply idle.
• Bandwidth of Channel is relatively narrow (30 KHz), known as narrowband system.
• Little or no equalization is needed for spreading symbol time.
• Analog links are suitable for FDMA.
• Framing or synchronization bits are not needed for continuous transmission.
• Tight filtering is needed to minimize interference.

39. What Are The Difference Between Tdma?

CDMA and TDMA : 

CDMA 

• Power limited system
• While people talking, random noise band playing occurs
• Conversation need to be extracted from the background din
• GP is high when people speak different languages, which is easier to distinguish individual speakers
• It is difficult for distinguishing individuals, when GP is low.
• The system performance will be degraded for every user when the number of users increases.
• Fading would be reduced with wide frequency spectrum
• Need to have separate multipath signals with different delays by “chip” unit.

TDMA : 

• Receiving or transmission is allowed for only one user in a given slot
• All slots are assigned cyclically
• The transmission is non-continuous
• It is essential to use digital data and modulation
• Data rate overhead is between 20% – 30%
• Overhead tradeoffs are size of data payload and latency
• Multiple users are shared with single carrier frequency
• Handoff is made simpler by using non-continuous transmission
• All slots are assigned on demand
• Due to reduced inter user interference, the power control is less stringent.

40. What Is The Difference Between Cdma And Gprs? Which Of Them Is Better? Why?

The Differences:

• CDMA is one of the types of mobile connections for making calls where as GPRS is a technology for internet connections through a mobile phone.
• GPRS enables to surf the internet from a mobile phone. GPRS technology is used in other gadgets apart from mobile phones.
• W-CDMA technology is faster than GPRS, since the user cares about the technology that is applied for air interface.
• Average latency on GPRS is around 1.3 seconds, where as on CDMA is around 400 milli second
• GPRS supports only User Datagram Protocol, where as CDMA supports both UDP and TCP
• GPRS relies on Network Address Translation and a private IP address is assigned to it. On the other hand CDMA assigns a public IP address CDMA is better because:
• E-mail is pretty light, until you enter MS-Office.
• Pocket PC’s support for office documents with similar functionality which can be had on Palm OS and Symbian
• Upon availability of APIs, a software developer could write various applications, like voice transfer, data transfer to client’s account, integrating billing amount etc.
• Web services could be utilized.

41. Explain Following Forward Link Channels In Cdma System: A.) Pilot Channel B.) Sync. Channel

Pilot Channel : 

• A forward link channel which is a base to mobile that modulates only by the pilot PN. It spreads common codes to all signals transmitted from a given base station.
• Several critical important functions are provided by the pilot channel for forward links in IS-95 systems
• The pilot channel modulation facilitates the process of time synchronized replica generation at the receiver of the PN spreading sequences. These are utilized at the transmitter for modulating the synchronization, paging and traffic channels. These are transmitted from the same base station.

Sync-Channel :

• A base station transmits a Sync-Channel that spreads with Walsh code 32.
• The frame of synch channel is 80/3ms long with frame boundary is aligned to the pilot.
• Sync channel transmits a single message continually, called Sync Channel Message.
• The Sync Channel Message contains network information, including the PN offset that is used by the Base Station sector.
• The length and content of the message is dependent on the P_REV.
• The message transmission rate is 32 bits / frame.
• The message is encoded to 128 symbols
• The message yielding rate is 1200 bits / s.

42. Explain The Following Two Types Of Hand Off In Cdma System: A.) Soft Handoff B.) Softer Handoff

Soft handoff : 

• Soft handoff is a feature in which a cellular phone is simultaneously connected to two or more cellular phones during a single call
• It is he overlapping of repeater coverage ones, which enables every cell phone set is always well within the range of a specific repeater.
• More than one repeater can send and receive signals to transmit signals to and from mobiles.
• All repeaters are used with the same frequency channel for each mobile phone set.
• Practically no dead zones and as result, the connections seldom interrupted or dropped. 

Softer handoff : 

• Softer handover is a significant soft handover in which the added and removed links belong to the same node.
• Macro diversity with maximum ratio combining could be performed in the same node.
• The movement of handoff, when a user can be served in another cell more efficiently (less power emission, less interference), is the most obvious cause for better performance.

43. What Is Gsm?

• Short form of Global System for Mobile Communications, is a wireless network system
• A standard for digital cellular mobile communications
• International roaming arrangements are enabled among mobile network operators, by providing the subscribers to use their personal mobile phones anywhere in the world.
• GSM is considered as second generation mobile, as signaling and speech channels are digital
• The carriers can be replaced without replacing mobile phones.
• The ubiquity of GSM implementations is also enabling the switching between network operators, who can choose equipment from many GSM equipment vendors.
• GSM pioneered low cost SMS implementation.
• The GSM standard includes a worldwide emergency telephone number feature.

44. Explain The Services Offered By Gsm.

• The services offered by GSM are ISDN compatible
• GSM allows synchronous data and asynchronous data to be transported as bearer service, one of the telecommunication services offered by GSM, and forms ISDN terminal
• The data could be either transparent service or nontransparent service
• Telephony is one of the services offered by GSM, which an emergency and the service provider is notified by dialing 3 digits
• By using appropriate fax adaptor, G3 fax service is supported
• One of the features of GSM is Short Messaging Service
• Certain services, namely supplementary services are provided on top of teleservices or bearer services by GSM, such as, caller identification, call forwarding, multiparty conversations, barring outgoing calls and call waiting.

45. What Is The Maximum Data Rate Supported By A Gsm System?

• The maximum data rate supported by a GSM system is 9.6 kbps.
• However there are extensions to GSM standard to improve throughput.
• GPRS is one of the extended GSM service.
• The extended standards of GSM allows theoretical data rates on the order of 114 Kbit/s, but with throughput closer to 40Kbit/s in practice.

46. Explain The Following Techniques In Gsm: A.) Sectorization Of A Cell B.) Frequency Re-use C.) Transmitted Power Control D.) Discontinuous Transmission

 Sectorization of a cell : 

• Sectorization is a process to cut down equipment costs in a cellular network. It influences in traffic load and cell size
• Sectorization reduces co-channel interference, when applied to clusters of cells
• The maximum traffic capacity of sectored antennas is more than omnidirectional antennas.

Frequency Re-use :

• Frequency re-use is the key factor of cellular network ability for increasing both coverage and capacity.
• Different frequencies are utilized by adjacent cells; however problem does not arise to determine the cell sufficiently far apart using the same frequency.
• Reuse distance and the reuse factor are the two elements that influence frequency reusability
• The frequency is 1/K, where K is the number of cells that cannot use the same frequencies for transmission.

Transmitted Power Control :

• Transmitted power control is one of the technical mechanism used within some networking devices
• TPC is used for preventing too much unwanted interference among wireless networks
• The central idea is to automatically reduce the transmission output power used, when other networks are within the same range.
• TPC reduces interference problems and increases the battery capacity
• The power levels of a single mobile device can be reduced by 6dB

Discontinuous Transmission : 

• Discontinuous Transmission, also known as DTX in short is a method of momentarily powering down a mobile set when there is no voice input to the set.
• The overall efficiency of a wireless voice communication system is optimized by DTX.
• Each speaker in a two way conversation speaks slightly less than half of the time.
• The workload of the components in the transmitter amplifiers are made easy and reduces interference. 

47. Which Uplink/ Downlink Spectrum Is Allocated To Following? A.) Gsm – 900 B.) Dcs – 1800

GSM – 900:
Uplink spectrum is 890.2–914.8 and downlink spectrum is 935.2–959.8

DCS – 1800:
Uplink spectrum is 1710.2–1784.8, and downlink spectrum is 1805.2–1879.8

48. Explain Equalisation?

 Equalisation: 

• An adaptive equalizer is employed by a GSM receiver for overcoming the impact of non-ideal channel characteristics which are caused by multipath propagation.
• Adaptive equalizer is required because the channel characteristics are often changing fast.
• Tuning the for each time slot is done by the equalizer.

49. Explain Interleaving?

Interleaving: 

• Time diversity in a signal communication system is obtained by using Interleaving.
• The possibility of losing whole bursts will be decreased by interleaving.
• Total 456 bits from convolution encoder, including 20ms of speech, is subdivided into eight blocks. Each block consists of 57 bits.
• All these blocks are transmitted in consecutive time slots.
• Enough information is available in 7 blocks, in case one of the blocks is lost due to burst errors. This enables whole segment recovery by using error correction.

50. Explain Speech Coding?

Speech coding:

• Speech coding is all about turning voice into digital form.
• Speech is inherently analog, as GSM is a digital system.
• The digitization is employed by ISDN, and the current telephone systems that are used for multiplexing voice lines, with high speed trunks, optical fiber lines is done by Pulse Code Modulation(PCM).
• The PCM output is 64 kbps, which is too high over a radio link in feasibility.
• The 64kbps signal is redundant.
• The algorithm used in conventional cellular is Vector Sum Excited Linear Predictive speech compression.

51. Explain Channel Coding?

Channel coding :

• The data rate for the radio channel is 270 kbps.
• The data rate is split into 8 full rate or 16 half rate traffic channels, along with signaling channels
• In order to have the maximum chance for detecting and correcting errors, the code is complex in a typical propagation path
• Forward Error Correction is applied in order to get the speech coder encryption, coding and interleaving in a sophisticated way
• The data is sent as bursts in 577 mus time slots. Each contains 116 encrypted bits
• Every TDMA frame consists of 8 or 16 time slots
• Transmit time slots are staggered, so that at some instant the mobile station will not receive the same instants while transmitting, which enables the simplifying the filtering requirements
• At least one spare slot between transmit and receive is available with this scheme.

52. What Is Frequency Re-use?

Frequency Re-use:

• Frequency re-use is one of the techniques for improving capacity and spectral efficiency.
• Commercial wireless systems are based on Frequency Reuse, that involves the partitioning of an RF radiation area into cell segments.
• A frequency that is far enough away from the frequency in the bordering segment is used by one segment of the cell.
• Similar frequency is used at least two cells apart from each other.
• This practice enables various cellular providers to have several customers for a given site license. 

53. Explain Gprs?

• Short form of General Packet Radio System.
• GPRS is the next generation of GSM, and the basis of the 3G networks.
• A packet oriented data service available to users of GSM and IS-136 type mobile phones.
• It complements the existing services like circuit-switched cellular phone connections and the SMS.
• Shortest set-up time is added for ISP connections.
• An optimized mobile service for sending and receiving information across a mobile telephone network, with less cost.
• GPRS provides data rates of mobile telephony and moderate speed data transfer, using unused TDMA channels.
• GPRS does not need dial-up modem connection.
• Sending and receiving e-mails, surfing internet are among the features of GPRS.

54. What Signals Are Transferred In Gprs?

• GPRS uses 2.5 generation of GSM signals.
• The radio interface is the same that of GSM.
• GPRS uses 900 / 1800 Mhz, frequency band and GMSK modulation.
• The bit rates are EGPRS, similar to EDGE.
• Separate hardware and ports need to be added and availed. 

55. How Are Gprs Terminals Classified?

• The GPRS services are classified into 12 service classes as per the duration of the time slots occupied / frame.
• Usually 5 time slots per frame are occupied including transmission time slots and reception time slots.
• Increase in the number of occupied time slots certainly causes the increase in the entire duration of the occupied time slots, so that increased amount of data transmission and receipt are enabled.
• All the 12 service classes are further classified into higher and lower classes as per the relative duration of time slots.
• Higher speed data communication can be transmitted with high-class GPRS service by setting high transmission power and setting the duration of the time slots long.

56. What Gross Data Rate Does Gprs Provide?

• GPRS is a packet oriented mobile data service.
• The data transfer is charged per megabyte of traffic.
• GPRS provide gross data rate of 22.80 KBPS / time slot.
• Voice uses only 13KBPS/ time slot and the rest is consumed by Error Correction Code.
• Error connection code is utilized for detecting and correcting the transmission errors.
• As voice is compressed, the usage of Error connection code is mandatory.
• In the 2G systems it provides a rate from 56 up to 114 kbits/s.

57. What Is Piggybacking In Context To Wi-fi?

Piggybacking is a term which states that something that is riding on the back of something else to complete his/her motive, just like similar to an idiom putting gun to another’s shoulder and performing Hunting, so piggybacking is a term used to refer to access of a wireless internet connection by bringing one’s own computer within the range of another’s wireless connection, and using that service without the subscriber’s explicit permission or knowledge. It is a legally and ethically controversial practice, with laws that vary in jurisdictions around the world. Piggybacking is an unauthorized tapping into another’s connection with a public utility.

For e.g.-
So piggybacking can take place like when I am accessing the wireless connection of my neighbour Wi-Fi without his/her knowledge by hacking his static ip address, then it would be possible for me to access the Wi-Fi connection of others.

58. What Are The Recommended Channels If You Are Setting Up Three Wlans And Want Minimum Interference Over There?

There is a need of selecting the channels for setting up WLANs, to communicate; all the components of a Wi-Fi network must use the same channel. In the Wi-Fi network in infrastructure mode (using an access point), it depends on the channel set at the access point.

For better results when using Wi-Fi, it is necessary to adjust the channel on the access point as well as configured on the client, to take the least use channel in your neighbourhood.

 To do this you can use software such as NetStumbler, which will list the neighbourhood Wi-Fi networks and channels used.

 Note:-
The channels most frequently used to select one as free as possible.

 So the recommended channels are as follows:-

• Channel 1: 2.412 MHz
• Channel 2: 2.417 MHz
• Channel 3: 2.422 MHz
• Channel 4: 2.427 MHz
• Channel 5: 2.432 MHz
• Channel 6: 2.437 MHz  

You can choose from these channels while setting up the WLANs.

59. How To Crack Wi-fi Network, If You Are Using Wep (wired Equivalent Privacy) Password With Backtrack?

• The first line of defense of your Wi-Fi network is encryption, which encodes the data transmitted between your PC and your wireless router.
•  WEP abbreviates (Wireless Encryption Protocol). It is a less-secure protocol than WPA (Wireless Protected Access). Since WEP is relatively easy to crack, so you have to use the same form on all devices on your network. If you have an older router that supports WEP only you’ll be best safest if you use 128-bit bit WEP keys but also check the manufacturer’s Web site for a firmware update that will add WPA support.
• Two of the most popular programs used for actually cracking the WEP key are Airsnort and Aircrack. Airsnort can be used with the .dump files that Kismet provides; and Aircrack can be use with .cap files that Airodump provides

60. Differentiate Between Ad-hoc And Infrastructure Topology And Also Explain With Their Advantages And Disadvantages?

Wireless networks typically work in one of two configurations:
Ad-Hoc or Infrastructure.

• Ad-Hoc is Latin meaning “for this purpose” so these are the networks which are basically created for some purpose. So these are the group of workstations which communicate directly witch each other to exchange information. An Ad-Hoc network is also called as a peer to peer network. 

Here are some benefits of an Ad-Hoc network are:-

• The possibilities with Ad-Hoc network are quite endless.
• Ad-Hoc networks are simple to set up.
• Ad-Hoc networks are inexpensive.
•  Ad-Hoc networks are fast.

Disadvantages of an Ad-Hoc network are as follows:-

• It is not able to get into the mainstream wired local area network.
• It needs more technology to support their reliability.
• As the network increases its speed slows down considerably.
• In Infrastructure mode, network includes an access point when the wireless clients connect to an access point, which in turn bridges to a network. Infrastructure network can pass information through a central information hub which can be both, hardware or software device on a computer. So under this devices in a wireless network are set up to communicate through an access point. 

An infrastructure network enables you to:-

• a) In this you do not have to control over the path your data takes.
• b) Connect to a wired network.
• c) Extend your wireless network’s range.
• d) Utilize roaming ability.

Disadvantages for Infrastructure network are:-

• 1. Use of more wireless access points.
• 2. This increase the cost of implementing a wireless network solution.

61. How Do You Secure A Wireless Network?

Key points for securing a wireless network are as follows:-

• Verify that your PC’s software firewall is turned on, and that Window’s file-sharing feature is off; it’s off by default in Window’s XP with Service Pack 2.
• Never send bank passwords, credit card numbers, confidential e-mail, or other sensitive data unless you’re sure you’re on secure site: Look for the lock icon in the bottom-right corner of your browser, as well as a URL in the address bar that begins with https. Such sites build in their own encryption.
• Always turn your Wi-Fi radio off when you’re not at a hotspot: Hackers can use it to create peer-to-peer Wi-Fi connections with your computer and access it directly.
• For better security, consider signing up for a paid subscription to a hotspot network such as Boingo or T-Mobile. Both companies provide connection software that encrypts your sessions automatically.

1. What Is Xaml? What Is The Difference Between Xml And Xaml?

XAML stands for extensible Application Markup Language. It is the language used to instantiate.NET objects. It is the language developed by Microsoft to write user interface for next generation applications.

XML is designed to store data or to work with the stored data, whereas XAML is the extended version of XML used for.NET programming.

2. Mention The Advantage Of Using Xaml?

The advantage of using XAML in

• XAML code is clear to read, and they are short.
• Separation of designer code and logic.
• Tools like expression blend used for graphical design require XAML as source.
• It clearly separates the roles of designer and developer.

3. How Can You Code To Display “hello World” In Xaml?

Displaying “Hello World.”

4. In Xaml How Graphic Components Are Specified?

In XAML, graphic components are specified with by open or closed tags with attributes.

For example:

Tag with contents

Click

Tag without contents

< Button/>

5. What Is Attribute Syntax In Xaml?

In XAML, attribute syntax sets a value for a property or names the event handler for an event, by declaring an attribute on an element. The attribute value should be enclosed within two quotation marks (“).

For example:

< Button Background = “Black” Foreground “Red” Content = “This is an operating button”/>

6. Explain Content Properties Xaml?

XAML represents a language feature whereby a class can allot exactly one of its properties as XAML property.

7. What Is Markup Extension In Xaml?

Markup extensions are placeholders in XAML that are used to resolve property at runtime. A markup extension allows you to extend XAML and using attribute syntax you can also set any property that can be set in XAML. The purpose of the mark up extension is to process a string and return an object. Some of the standard markup extensions are null, x: Array, :Static Resource and Dynamic Resource.

8. What Are The Four General Kinds Of Xaml Elements?

The four general kind of XAML elements are

• Root Elements
• Panel Elements
• Control Elements
• Geometric Elements

9. What X: Prefix Indicates In Xaml?

The X: prefix is used to map the XAML namespace in templates.

10. What Are The Various X: Prefix Used In Xaml Language?

• x: Key à It sets a unique key for each resource in a Resource Dictionary.
• x: Class It specifies the CLR ( Common Language Runtime) namespace and class name for the class that provides code.
• x: Name à It specifies a run-time object name for the instance that exist in run time code after an object element is processed.
• x: Static à It enables a reference that returns a static value which otherwise an XAML compatible property.
• x: Type à It constructs a Type reference based on the type name.

11. How Can You Set A Property Attribute As A Literal String And Not A Markup Extension?

To avoid mark up extension you have to use an empty pair of curly braces like

Content = “{} {This is not a markup extension}”/>

12. What Are The Types Of Children Does Object Element Can Have In Xaml?

Three types of children an object element can have:

• Collection Items
• A value for the content property.
• The value that can be type-converted to the object element.

13. Explain What Is Type Converter?

The type converter is helpful to convert a string into the appropriate value type where there is no markup extension usage. Type Converter defines four members for converting to and from string for Xaml purposes.

• CanConvertTo
• CanConvertFrom
• Convert To
• Convert From

14. Explain Object Element Syntax In Xaml?

To instantiate a CLR class or structure by declaring an XML element, an XAML markup syntax is used. This syntax is referred as Object Element Syntax.

15. What Are The Ways You Can Declare Objects In Xaml?

To declare objects in XAML, there are three ways:

Directly, using object element syntax:
This syntax is used to declare root objects or nested objects that set property values.

Indirectly by using attribute syntax:
This syntax uses an inline string value which has an instruction on how to create an object. To set the value of the property to a newly created reference, the XAML parser uses this string.

16. What Should A Root Element Of An Xaml Document Contain?

In XAML document, the root element consists only certain elements, and these elements are Window, a Canvas or panels.

17. What Is Data Binding With Xaml?

Data binding provides a simple way to display and interact with data. An example will show how you can do data binding in XAML. The binding in XAML is done by using {binding….} syntax.

18. Explain How You Can Display Different Data At Run Time And Design Time?

One way of displaying data at run time and design time is to declare your data in XAML.

Another way of doing it is by declaring it in XAML by using various data attributes from the designer XML namespace. With a d: prefix, this namespace is typically declared.

xmlns: d= http://schemas.microsoft.com/expression/blend/2008

19. Explain What Is The Function X: Key Directive In Xaml?

X: Key uniquely identifies elements that are created and referenced in an XAML defined dictionary. By adding an x: Key value to an XAML object element a resource in the resource dictionary can be identified and is the most common way to identify.

20. Explain What Is The Use Of Property Element Syntax?

With the help of property element syntax, you can add children element with a name in the form of parent.propertyName.

21. How Custom Classes Used In Xaml Can Be Defined?

Custom classes are used in two ways:

1. With the code that produces the Primary Windows Presentation Foundation (WPF) application or within the code behind.
2. In a separate assembly as a class, such as an executable or DLL used as a class library.

22. What Is Xaml Namespace?

Namespace can be defined as an environment or an abstract container used to hold a logical grouping of unique identifiers or symbols.

1. How Are The Difficulties Involved With Testing Of Mobile And Cellular Handsets Overcome By Testers?

The most common and important difficulties that should be overcome by testers is testing on multiple types of handsets and automation testing.

2. How Can You Overcome The Difficulties Involved With Testing Of Mobile And Cellular Handsets?

As a tester you need to make yourself more aware of the automation services/tools to run tests on mobiles handsets.

A smart mobile simulation program is hooked on to the actual (physical) handset at ‘device anywhere’ site. Companies pay per use or a monthly fee. The UI is like that of a mobile simulator, but the tests run on a phone.

The beauty lies in the variety of mobile phones they offer. I’m no way connected to device anywhere company but I’m a customer who is benefiting from their service.

3. Explain What Technologies Are Used With Wireless Testing?

The technology used will determine the type of test environment and tools that we need.

• WAP.
• Bluetooth, etc..
• XML, WML.
• Security protocols.

Tools: 

• WAP Simulators by hardware vendor: Nokia, Ericsson, Motorola.
• Capture/Playback – such as TestPartner by Compuware.
• Performance Testing – such as QA Load Compuware.

4. What Is Wireless Test Executive?

Wireless test executive is an easy-to-use graphic interface for controlling test selection, execution, and runtime options. Tests are displayed in a hierarchical list where each entry represents one test.Test Objects are a key component of the Test Executive Architecture.The Test Objects operate with the Test Executive through a standard interface that is provided by the Test Executive DLL.

5. Explain What Is The Term Load In Wireless Testing?

Its giving enough load to the process. Suppose a user using the wireles interface for communication, which it is many-many communicator.

• Check the interface behaves once another communicator is in request(make a call to a interface, which is busy in communcating with another interface).
• Check the Wireless interface performance on invoking the another application( Reminder, Alaram invoked on call, Message received, low battery ect..)

6. What Are The Different Levels In Wireless Testing?

Levels of testing:

1. Usability Testing
2. Network Performance Testing
3. Server-Side Testing
4. Automating Unit Testing

7. Explain How Is Quality Of Wireless Testing Measured?

The quality of a wireless signal is measured with respect to thresholds of:

• BER (Bit Error Rate) which should be < 10^-6 or BLER (Block Error Rate)
• RSSI (Received Signal Strength Indicator)
• SWR (Standing Wave Ratio)
• SNR (Signal-to-Noise Ratio) which is P/N
• SINR (Signal to Interferance and Noise Ratio) or P/(N+I)
• SINADR (Signal-to-Interference plus Noise And Distortion Ratio).. and many more.

These parameters are evaluated based on the technology or standard in use. For example, in WiFI or 802.11, the RSSI is used as the link quality parameter to be used. However, all of the above contribute in one way or the other to the quality of the wireless link as noise, interference, environmental characteristics, power, frequency used… contribute to the loss or gain in the link’s quality.

8. Explain Requirement Of Simulators?

Best way to test network apps to test connectivity.

9. Build Installation Medium?

Wireless (OTA/WiFi/BT) wired: using Data Cable, PC Suit.

10. Builds For Devices?

sort out builds on basis of :

• make (Brand) due to their specific key functionalities.
• resolutions 128×128, 240×320, 176×220 (208), 320×240 or higher resolution.

11. Find Out What To Test? Is The Application In Stand Alone Or Client Server?

If application is clent server – you need wifi (if Device support) and GPRS (device should be enbled and GPRS Access Points should be configured according to requirement).

For CDMA there is no need to set access point. And devices should be according to service operators.

12. How Is Test Environment Prepared For Wireless Testing?

There are wireless simulators to which you connect ur mobile and test. Simulator acts like wireless tower in real network

13. Is There Any Automation Tool For Mobile(wireless) Application Testing?

• TestQuest and MTS are two mobile automation tools. 
• TestQuest is used to test wireless handsets.
• MTS is a scalable automated application testing tool for Windows Mobile 5.0.
• There are also ways to produce automated tests on various mobile browsers with wireless handset simulation tools such as OpenWave.

14. Explain What Is Wireless Testing? How Do We Do It? What Are The Concepts A Test Engineer Should Have Knowledge Of? How Do U Classify Testing Of Wireless Products?

Wireless testing you can classify into 3 types:

1. Platform testing:
   To do this testing, tester should have programming knowledge of cpp, java
2. Protocol testing:
   To do this, tester should have a knowledge of Networking concepts like, making lan connections, read protocol logs in wireshark, ethereal (both are protocol logging tools), all protocol definitions TCP/IP, UDP.. etc etc
3. Application testing
   : Testing mobile application is almost testing windows applications but bit different. Some basic networking concepts are must. If the application is to be testing in JUnit, then Java knowledge is a must.

15. Explain How Must The Testers Update Themselves And What All Must Be Learn By Testers To Perform Wireless Testing?

1. Should know the Functional units for new technology.
2. Tester should know the latest Mobile technology knowledge.
3. Should know about the Test Environment.
4. Should able to configure and troubleshoot the device.
5. Should able to follow the standards and verify the checklist.
6. Should be innovative thinking and make Test scenario for the running the application.
7. Should able to Test the full part of coverage.

16. What Are The Prerequisites To Become A Mobile Tester?

Mobile Tester Should know about the

1. Mobile Technology
2. Development Technology
3. Mobile Platform(OS)
4. Knowledge on Device Supporting Tools.
5. Mobile Protocols

17. How To Test Protocols In Mobile Testing. And How Many Protocols Are Used In Mobile Application?

Actually the same TCP/IP concepts go in mobile apps also, but when it comes down to browsing apps/downloading apps, it is generally done via WAP gateway (Not WAP Server which generally people confuse with). WAP is a standard defined to serve as a common platform as we cannot directly hook on from normal TCP/IP network to a mobile network. But it is definitely possible to call, SMS, sending mail from any browser to a mobile device, and vice versa. 

18. Explain Difference Between 2g And 3g In Mobile Phone Testing?

2G and 3 G is a family of standards for mobile telecommunications defined by the International Telecommunication Union,which includes GSM EDGE, UMTS, and CDMA2000 as well as DECT and WiMAX. Services include wide-area wireless voice telephone, video calls, and wireless data, all in a mobile environment.

2G Stands for second generation mobile telephony standards, where 3G defined the third generation mobile telephony standards to facilitate growth, increase bandwidth, and support more diverse applications.For example, GSM (the current most popular cellular phone standard) could deliver not only voice, but also circuit-switched data at download rates up to 14.4 kbps. But to support mobile multimedia applications, 3G had to deliver packet-switched data with better spectral efficiency, at far greater bandwidths.

19. What Areas Of Applications Can Be Covered Under Wireless Testing?

Basically Call module should be covered for wireless testing, after that all the applications should be tested how those applications behave when a call is received being in that application.

20. Explain How Are The Security Aspects Taken Care While Performing Wireless Testing In A Wireless Network?

we must consider the following aspect:

1. Unauthorised access/Guest access
2. Firewalls
3. Concurrent connections

21. How To Get Voice Over Wireless Testing?

There are testlabs to test the voice over wireless testing. Otherwise you can use two of ur test mobiles and can put any operators simcard just like ur own mobile and can test it. Most of the companies provide some operators simcards to test.

22. How We Test Battery Back Up Time Using Load Testing?specially For Mobile Testing?

procedure of battery testing :

battery backup test for idle mode:

• fully charge the battery
• make sure no calls should be made on DuT
• start timer when fully charget
• wait until the battery drain out fully 

battery backup test for dedicated mode:

• again fully charge the battery 
• make a call to a test phone from DuT
• start timer when call is connected
• wait untill the battery is fully drain out 
• match all the readings from user manual and check the battery leakage

23. Abbreviate Tls And Ttls?

• TLS:
  Transport Layer Security
• TTLS:
  Tunneled Transport Layer Security

24. Abbreviate Wep And Tkip?

• WEP:
  Wired Equivalent Privacy
• TKIP:
  Temporal Key Integrity Protocol

25. How Can We Utilize Racal In Mobile Testing?

RACAL is Base station emulator, using this we can test all mobile use cases in the controlled environment.

26. How Is Wireless Network Adapters Tested?

• Check that the Wireless Network Adapter is on and verified by LED glow.
• Check that the Wireless Network Adapter is suited for the different OS.
• Check the Wireless Network Adapter is able to pass Installation Testing.
• Check that the Wireless Network Adapter is able to configure.
• Check the data flows(in/out) functions for the Wireless Network Adapter.
• Check the flow rate of data and should not breakup.
• Check the Time delay taken for every process.
• Data Transmission should not be freeze at any situation.

27. How To Do Tracing In Wireless Testing?

1. Wired-side AP fingerprinting
2. Wired side MAC prefix analysis
3. Wireless-side warwalking
4. Wireless-side client monitoring
5. Wireless-side WLAN IDS 

28. Which Areas Of The Application Can Be Covered Under Wireless Testing?

Call modules should be tested for wireless testing, after that all the applications should be tested to check how those applications behave when a call is received in that application.

29. What Should The Testers Know To Able To Perform Wireless Testing Effectively?

Testers must be able to think lot of scenarios relating to calls, for example when a call comes and at the same time alarm rings how the system behaves or say when the mobile is busy with a call at that time one more call comes, how the system behaves etc. There can be a lot of scenarios like this.

30. How Should The Analysis Be Performed By A Tester Before Carrying Out Wireless Testing?

White box testing provides the testers with complete knowledge of the infrastructure to be tested, often including network diagrams, source code, and IP addressing information. 

It can be performed to validate whether code implementation follows intended design, to validate implemented security functionality, and to uncover exploitable vulnerabilities.

1. What Is Yum Server ?

The Yellowdog Updater, Modified (yum) is an open-source command-line package-management utility for Linux operating systems using the RPM Package Manager. Though yum has a command-line interface, several other tools provide graphical user interfaces to yum functionality. Yum allows automatic updates, package and dependency management, on RPM-based distributions. Like the Advanced Packaging Tool (APT) from Debian, yum works with software repositories (collections of packages), which can be accessed locally or over a network connection.

Advantages of Yum Server:

• Automatic resolution of software dependencies. If a package installation or upgrade request is made and requires the installation or upgrade of additional packages, YUM can list these dependencies and prompt the user to install or upgrade them.
• Command-line and graphical versions. The command-line version can be run on a system with a minimal number of software packages. The graphical versions offer ease-of-use and a user-friendly graphical interface to software management.
• Multiple software locations at one time. YUM can be configured to look for software packages in more than one location at a time.

2. How To Install Packages Using Yum ?

yum install package_name

3. How To Update The Package Using Yum ?

yum update package_ name

4. How To Search The Package In Yum ?

yum search package_name

5. How To Remove The Package Using Yum ?

yum remove package_name

6. How To Check The Updates For Yum Repository ?

yum check-update

7. How To Update The Yum Repo ?

yum update

8. How To Get The Package Information Using Yum ?

yum info package_name

9. How To List The Installed Packages On Redhat Linux Using Yum Command ?

yum list installed

10. How To Know The Particular Files Belongs To Which Package ?

yum provides file_path

Ex:

[root@mylinz ~]# yum provides /etc/yum.conf

Loaded plugins: refresh-packagekit, rhnplugin

This system is not registered with RHN.

RHN support will be disabled.

yum-3.2.27-14.el6.noarch :
RPM installer/updater

Repo       
: local-installation

Matched from:

Filename    :
/etc/yum.conf

yum-3.2.27-14.el6.noarch :
RPM installer/updater

Repo       
: installed

Matched from:

Other       
: Provides-match: /etc/yum.conf

11. How To List The Enabled Repositories ?

yum repolist

12. Which Option Is Required To Assume The Answer “yes” To Any Questions Asked During Installation Of Package Dependencies For Yum?

The “-y” option is used to assume the answer “yes”.

For Example:

yum -y install squid

1. What Is Zimbra ?

Zimbra provide enterprise-class and open-source edition. Email, calendar and groupware software for Linux and MAC operating system.

2. How To Create Email Account On Command Line ?

zmprov createAccount firstname.lastname@example.com password displayName “firstname lastname”

3. How To Reset Email Account Password ?

zmprov sp firstname.lastname@example.com NEW_PASSWORD

4. How To Check Zimbra Services Are Running Or Not Running ?

zmcontrol status or you can view with admin panel of zimbra over GUI.

5. How To Start Only Mta Services Of Zimbra If It’s Not Running ?

zmprov -l ms mail.example.com +zimbraServiceEnabled mta

6. How To Check Zimbra Server Version Which You Have To Use?

zmcontrol -v

Release 7.1.1_GA_3196.UBUNTU10_64 UBUNTU10_64 FOSS edition.

7. How To Set Forwarder And How Much Limit For Forwarding Email Id?

You can go through Admin penal over GUI interface and select specific user account, edit account and go to Forwarder tab. and you can set Forwarding Email id and Forwarder limit is only 100 ID’s.

8. What Are Key Differences Between Open Source Zimbra And Network Edition Of Zimbra Server?

Clustering/High-Availability feature is available in network edition of zimbra server. Hot Backup is also possible in zimbra network edition Email Archiving & Discovery is not possible in open source zimbra server. Real-time backup and restore is also possible in network edition of zimbra server.

9. Is It Possible To Mix Zcs Open Source Edition Accounts With Network Edition Accounts In One Installation?

Unfortunately you can not mix them, but there are multiple versions of Network Edition available to meet varying needs.

10. How To Take Backup Of Zimbra ?

At first you have to need stop the zimbra services and then rsync /opt/zimbra directory on another backup systems.

eg:– su zimbra

zmcontrol stop

ps auxww | grep zimbra

11. How Much Storage Does Each Zimbra Account Come With?

If you are installing ZCS on premise then storage is only limited by how much physical storage space you wish to allocate to each account eg:– it can be unlimited, 10GB, 2GB 13MB, etc) depending on hardware constraints. The Administration Console allows IT team to easily set up “Class of Service” for the accounts.

12. How To Fix Quota Limit On Zimbra Account?

You can go through Admin panel over GUI interface and select specific user account, edit account and go to Advanced tab. and you can set quota limit.

13. How Much Create Email Account On Zimbra Mail Server ?

unlimited..

14. Where Is Log File Of Zimbra?

cat /var/log/zimbra.log and also you can view # tail -100f /var/log/mail.log

15. What Happens When My Network Edition 60 Day Trial License Expires?

Your basic ZCS features will still be working, but the following occurs:

• You can no longer add new user accounts
• Zimbra Mobile and the Zimbra Outlook & iSync Connectors will be disabled
• Administrators will see an alert message when they log into the Admin console

16. How To Made Mirror Server For Live Data Sync ?

Exactly the same version of Zimbra must be installed on both the live and mirror server. To start with we work on the live server. There is no need to stop Zimbra for most of the install. Only a short amount of down-time will need to be scheduled later to perform a final rsync operation between the two servers.

Go As user root….

# apt-get install inotify-tools on both server Main and Mirror server.

service zimbra stop on Mirror server.

# rsync -aHz –force –delete live_server:/opt/zimbra/ /opt/zimbra/

# service zimbra start

service zimbra start

service zimbra status

17. What Phones Are Supported By Zimbra Mobile?

All Windows Mobile 5 devices Symbian S60 and S80 devices like the Nokia E-Series, Palm devices like the Treo 700P sync natively with Zimbra. (Some require additional 3rd party plugins) Blackberry is supported through a third party partner.