Category: Computer Networks Objective Questions

Computer Networks Multiple Choice Questions on “IP Routing”.

1. Which type of Ethernet framing is used for TCP/IP and DEC net?
a) Ethernet 802.3
b) Ethernet 802.2
c) Ethernet II
d) Ethernet SNAP

Answer: c
Clarification: The Ethernet 802.3 framing is used for NetWare versions 2 to 3.11, and the Ethernet 802.2 framing is used for NetWare versions 3.12 and later plus OSI routing, Ethernet II is used with TCP/IP and DEC net, and Ethernet SNAP is used with TCP/IP and AppleTalk. The type field in Ethernet 802.2 frame is replaced by a length field in Ethernet 802.3.

2. Consider a situation in which you are a system administrator on a NetWare network, you are running NetWare 4.11 and you cannot communicate with your router. What is the likely problem?
a) NetWare 4.11 defaults to 802.2 encapsulation
b) NetWare 4.11 defaults to 802.3 encapsulation
c) Cisco routers only work with NetWare 3.11
d) NetWare 3.11 defaults to 802.2 encapsulation

Answer: a
Clarification: The default encapsulation on Cisco routers is Novell Ethernet_802.3 and NetWare 3.12and later defaults to 802.2 encapsulation, 3.11 and earlier defaults to 802.3.

3. NetWare IPX addressing uses a network number and a node number. Which statement is not true?
a) The network address is administratively assigned and can be up to 16 hexadecimal digits long
b) The node address is always administratively assigned
c) The node address is usually the MAC address
d) If the MAC address is used as the node address, then IPX eliminates the use of ARP

Answer: b
Clarification: The network address can be up to 16 hexadecimal digits in length. The node number is 12 hexadecimal digits. The node address is usually the MAC address. An example IPX address is 4a1d.0000.0c56.de33. The network part is 4a1d. The node part is 0000.0c56.de33. The network number is assigned by the system administrator of the Novell network and the MAC address/node address is not assigned by the administrator.

4. Which NetWare protocol works on layer 3–network layer—of the OSI model?
a) IPX
b) NCP
c) SPX
d) NetBIOS

Answer: a
Clarification: IPX (Internetwork Packet Exchange) is the NetWare network layer 3 protocol used for transferring information on LANs that use Novell’s NetWare.

5. Which NetWare protocol provides link-state routing?
a) NLSP
b) RIP
c) SAP
d) NCP

Answer: a
Clarification: NetWare Link Services Protocol (NLSP) provides link-state routing. SAP (Service Advertisement Protocol) advertises network services. NCP (NetWare Core Protocol) provides client-to-server connections and applications. RIP is a distance vector routing protocol. NLSP was developed by Novell to replace RIP routing protocols.

6. As a system administrator, you want to debug IGRP but are worried that the “debug IP IGRP transaction” command will flood the console. What is the command that you should use?
a) Debug IP IGRP event
b) Debug IP IGRP-events
c) Debug IP IGRP summary
d) Debug IP IGRP events

Answer: d
Clarification: The “debug IP IGRP events” is used to display a short summary of IGRP routing information. You can append an IP address onto either console’s command-line to see only the IGRP updates from a neighbor. The command will only give a short summary and hence won’t flood the command line.

7. What does the following series of commands “Router IGRP 71 network” accomplish?
10.0.0.0 router IGRP 109 network 172.68.7.0
a) It isolates networks 10.0.0.0 and 172.68.7.0
b) It loads IGRP for networks 109 and 71
c) It disables RIP
d) It disables all routing protocols

Answer: a
Clarification: It isolates network 10.0.0.0 and 172.68.7.0 and associates autonomous systems 109 and71 with IGRP. IGRP does not disable RIP, both can be used at the same time.

8. The “IPX delay number” command will allow an administrator to change the default settings. What are the default settings?
a) For LAN interfaces, one tick; for WAN interfaces, six ticks
b) For LAN interfaces, six ticks; for WAN interfaces, one tick
c) For LAN interfaces, zero ticks; for WAN interfaces, five ticks
d) For LAN interfaces, five ticks; for WAN interfaces, zero Ticks

Answer: a
Clarification: Tick is basically the update rate of clients in the network. The IPX delay number will give the ticks at a certain time. The default ticks are–for LAN interfaces, one tick, and for WAN interfaces, six ticks.

9. As a system administrator, you need to set up one Ethernet interface on the Cisco router to allow for both sap and Novell-ether encapsulations. Which set of commands will accomplish this?
a) Interface Ethernet 0.1 IPX encapsulation Novell-ether IPX network 9e interface
Ethernet 0.2 IPX network 6c
b) Interface Ethernet 0 IPX encapsulation Novell-ether IPX network 9e interface
Ethernet 0 IPX encapsulation sap IPX network 6c
c) Interface Ethernet 0.1 IPX encapsulation Novell-ether interface Ethernet 0.2 IPX
encapsulation sap
d) Interface Ethernet 0.1ipx encapsulation Novell-ether IPX network 9e interface
Ethernet 0.2 IPX encapsulation sap IPX network 6c

Answer: d
Clarification: The following commands setup the sub interfaces to allow for two types of encapsulation:interface Ethernet 0.1 IPX encapsulation Novell-ether IPX network 9e interface Ethernet0.2 IPX encapsulation sap IPX network 6c.

10. What does the “IPX maximum-paths 2” command accomplish?
a) It enables load sharing on 2 paths if the paths are equal metric paths
b) It sets up routing to go to network 2
c) It is the default for Cisco IPX load sharing
d) It enables load sharing on 2 paths if the paths are unequal metric paths

Answer: a
Clarification: It enables load sharing on 2 paths if the paths are equal metric paths. The default is 1 path and the maximum is 512 paths. The value must always be greater than 1 and must be a natural number.

11. You want to enable both arpa and snap encapsulation on one router interface. How do you do this?
a) The interface can handle multiple encapsulation types with no extra configuration
b) Assign two network numbers, one for each encapsulation type
c) Enable Novell-ether to run multiple encapsulation types
d) Both arpa and snap are enabled by default so you don’t have to configure anything

Answer: b
Clarification: To assign multiple network numbers, you usually use sub interfaces. A sample configuration follows: IPXEthernet 0.1 IPX encapsulation novell-ether ipx network 9e interface ethernet 0.2 ipx encapsulation sap ipx network 6c

12. By default, Cisco routers forward GNS SAPs to remote networks.
a) False
b) True

Answer: a
Clarification: GNS is Novell’s protocol to Get Nearest Server. If there is a server on the local network,that server will respond. If there isn’t, the Cisco router has to be configured to forward theGNS SAP.

13. To prevent Service Advertisements (SAPs) from flooding a network, Cisco routers do not forward them. How are services advertised to other networks?
a) Each router builds its own SAP table and forwards that every 60 seconds
b) Each router assigns a service number and broadcasts that
c) SAPs aren’t necessary with Cisco routers
d) Cisco routers filter out all SAPs

Answer: a
Clarification: Cisco routers build SAP tables and forward the table every 60 seconds. All SAPs can’t befiltered even with 4.x since NDS and time synchronization uses SAPs.

14. Novell’s implementation of RIP updates routing tables every _________ seconds.
a) 60
b) 90
c) 10
d) 30

Answer: a
Clarification: Novell’s RIP updates routing tables every 60 seconds, Apple’s RTMP is every 10 seconds, routers ARP every 60 seconds, IGRP signal every 90 seconds, and Banyan VINES signals every 90 seconds.

15. In Novell’s use of RIP, there are two metrics used to make routing decisions. Select the correct metrics.
a) Ticks & Hops
b) Hops & Loops
c) Loops & Counts
d) Counts & Ticks

Answer: a
Clarification: It first uses ticks (which is about 1/18 sec.); if there is a tie, it uses hops; if hops are equal, then it uses an administratively assigned tiebreaker.

Computer Networks Multiple Choice Questions on “Reference Models”.

1. OSI stands for __________
a) open system interconnection
b) operating system interface
c) optical service implementation
d) open service Internet

Answer: a
Clarification: OSI is the abbreviation for Open System Interconnection. OSI model provides a structured plan on how applications communicate over a network, which also helps us to have a structured plan for troubleshooting. It is recognized by the ISO as the generalized model for computer network i.e. it can be modified to design any kind of computer network.

2. The number of layers in ISO OSI reference model is __________
a) 4
b) 5
c) 6
d) 7

Answer: d
Clarification: In OSI reference model, there are 7 layers namely Application, Presentation, Session, Transport, Network, Data Link and Physical layer. Each layer uses a protocol to perform its designated function, for example, the data link layer uses error detection protocols for error control functions.

3. TCP/IP model does not have ______ layer but OSI model have this layer.
a) session layer
b) transport layer
c) application layer
d) network layer

Answer: a
Clarification: In OSI reference model, there are two layers which are not present in TCP/IP model. They are Presentation and Session layer. The functions of Presentation and Session layer in the OSI model are handled by the transport layer itself in TCP/IP.

4. Which layer is used to link the network support layers and user support layers?
a) session layer
b) data link layer
c) transport layer
d) network layer

Answer: c
Clarification: Physical, data link and network layers are network support layers and session, presentation and application layers are user support layers. The transport layer links these layers by segmenting and rearranging the data. It uses protocols like TCP and UDP.

5. Which address is used on the internet for employing the TCP/IP protocols?
a) physical address and logical address
b) port address
c) specific address
d) all of the mentioned

Answer: d
Clarification: The physical, logical, port and specific addresses are used in TCP/IP protocol. All the addressing schemes, that is physical (MAC) and logical address, port address and specific address are employed in both TCP/IP model and OSI model. In TCP/IP, the addresses are more focused on the internet implementation of these addresses.

6. TCP/IP model was developed _____ the OSI model.
a) prior to
b) after
c) simultaneous to
d) with no link to

Answer: a
Clarification: Several TCP/IP prototypes were developed at multiple research centers between 1978 and 1983, whereas OSI reference model was developed in the year 1984. TCP/IP was developed with the intention to create a model for the Internet while OSI was intended to be a general network model.

7. Which layer is responsible for process to process delivery in a general network model?
a) network layer
b) transport layer
c) session layer
d) data link layer

Answer: b
Clarification: The role of Transport layer (Layer 4) is to establish a logical end to end connection between two systems in a network. The protocols used in Transport layer is TCP and UDP. The transport layer is responsible for segmentation of the data. It uses ports for the implementation of process-to-process delivery.

8. Which address is used to identify a process on a host by the transport layer?
a) physical address
b) logical address
c) port address
d) specific address

Answer: c
Clarification: A port number is a way to identify a specific process to which an Internet or other network message is to be forwarded when it arrives at a server. Some examples of port numbers are port 20 which is used for FTP data, port 22 which is used for SSH remote login ,and port 23 which is used for TELNET.

9. Which layer provides the services to user?
a) application layer
b) session layer
c) presentation layer
d) physical layer

Answer: a
Clarification: In networking, a user mainly interacts with application layer to create and send information to other computer or network. Application layer provides the interface between applications and the network. It is the top-most layer in both the TCP/IP and the OSI model.

10. Transmission data rate is decided by ____________
a) network layer
b) physical layer
c) data link layer
d) transport layer

Answer: b
Clarification: Physical layer is a layer 1 device which deals with network cables or the standards in use like connectors, pins, electric current used etc. Basically the transmission speed is determined by the cables and connectors used. Hence it is physical layer that determines the transmission speed in network. Some of the cables used for high speed data transmission are optical fiber cables and twisted pair cables.

Computer Networks Multiple Choice Questions on “FTP”.

1. Expansion of FTP is __________
a) Fine Transfer Protocol
b) File Transfer Protocol
c) First Transfer Protocol
d) Fast Transfer Protocol

Answer: b
Clarification: File Transfer Protocol is an application layer protocol used to share “files” between a server and a client. The protocol uses two separate ports for data and control connections: port 20 for data and port 21 for control.

2. FTP is built on _____ architecture.
a) Client-server
b) P2P
c) Data centric
d) Service oriented

Answer: a
Clarification: An FTP connection includes a Server and a Client which wish to share a number of data files. The server can transfer files with multiple clients at the same time while the client communicates with only one server at a time.

3. FTP uses _________ parallel TCP connections to transfer a file.
a) 1
b) 2
c) 3
d) 4

Answer: b
Clarification: Control connection using FTP port: 21, and data connection using FTP port: 20. The FTP session is started or ended using port 21 and the actual data i.e. files are sent through port 20.

4. Identify the incorrect statement regarding FTP.
a) FTP stands for File Transfer Protocol
b) FTP uses two parallel TCP connections
c) FTP sends its control information in-band
d) FTP sends exactly one file over the data connection

Answer: c
Clarification: FTP is out-of-band because the data connection is done separately through port 20 and control connection is done separately through port 21.

5. If 5 files are transferred from server A to client B in the same session. The number of TCP connections between A and B is _______
a) 5
b) 10
c) 2
d) 6

Answer: d
Clarification: The client would first initiate the TCP control connection through port 21. Then for every file transfer, a separate connection would be made through port 20. Now, since we have five files to be transferred, 1 control connection + 5 data connections = 6 total TCP connections.

6. FTP server _____________
a) Maintains state information
b) Is stateless
c) Has single TCP connection for a file transfer
d) Has UDP connection for file transfer

Answer: a
Clarification: FTP server maintains state information of every control connection to keep track of the active and inactive connections in the session. This helps the server decide which connection to terminate, in case the connection is inactive for too long.

7. The commands, from client to server, and replies, from server to client, are sent across the control connection in ________ bit ASCII format.
a) 8
b) 7
c) 3
d) 5

Answer: b
Clarification: FTP was designed to transmit commands only in English characters that are possible with just 7 bits in ASCII. Even the media has to be converted to ASCII before transmission.

8. Find the FTP reply whose message is wrongly matched.
a) 331 – Username OK, password required
b) 425 – Can’t open data connection
c) 452 – Error writing file
d) 452 – Can’t open data connection

Answer: d
Clarification: The correct response code for the message “Can’t open data connection” is 425. Response code 452 is sent usually when the connection is suddenly closed.

9. The data transfer mode of FTP, in which all the fragmenting has to be done by TCP is ________
a) Stream mode
b) Block mode
c) Compressed mode
d) Message mode

Answer: a
Clarification: Stream mode is the default mode of FTP, in which the TCP transforms/fragments the data into segments, and then after the transmission is completed, converts it back to stream of bytes.

10. The password is sent to the server using ________ command.
a) PASSWD
b) PASS
c) PASSWORD
d) PWORD

Answer: b
Clarification: The PASS command, preceded by the username, completes the user’s identification for access control in an FTP session. Without the valid password, the user won’t be able to initiate the FTP connection.

Computer Networks Multiple Choice Questions on “Congestion Control”.

1. Two broad categories of congestion control are
a) Open-loop and Closed-loop
b) Open-control and Closed-control
c) Active control and Passive control
d) Active loop and Passive loop

Answer: a
Clarification: Open loop congestion control techniques are used to prevent congestion before it even happens by enforcing certain policies. Closed loop congestion control techniques are used to treat congestion after it has happened.

2. In open-loop control, policies are applied to __________
a) Remove after congestion occurs
b) Remove after sometime
c) Prevent before congestion occurs
d) Prevent before sending packets

Answer: c
Clarification: Open loop congestion control techniques are used to prevent congestion before it even happens by enforcing certain policies. Retransmission policy, window policy and acknowledgement policy are some policies that might be enforced.

3. Retransmission of packets must not be done when _______
a) Packet is lost
b) Packet is corrupted
c) Packet is needed
d) Packet is error-free

Answer: d
Clarification: Retransmission refers to the sender having to resend the packet to the receiver. It needs to be done only when some anomaly occurs with the packet like when the packet is lost or corrupted.

4. In Go-Back-N window, when the timer of the packet times out, several packets have to be resent even some may have arrived safe. Whereas in Selective Repeat window, the sender resends ___________
a) Packet which are not lost
b) Only those packets which are lost or corrupted
c) Packet from starting
d) All the packets

Answer: b
Clarification: In Selective Repeat, the sender side uses a searching algorithm to find the packets which need to be retransmitted based on the negative acknowledgements received and then resends only those packets thus saving bandwidth.

5. Discarding policy is mainly done by _______
a) Sender
b) Receiver
c) Router
d) Switch

Answer: c
Clarification: The discarding policy adopted by the routers mainly states that the routers discard sensitive or corrupted packets that it receives, thus controlling the integrity of the packet flow. The discarding policy is adopted as an open loop congestion control technique.

6. Closed-Loop control mechanisms try to _________
a) Remove after congestion occurs
b) Remove after sometime
c) Prevent before congestion occurs
d) Prevent before sending packets

Answer: a
Clarification: In closed loop congestion control, methods are implemented to remove congestion after it occurs. Some of the methods used are backpressure and choke packet.

7. The technique in which a congested node stops receiving data from the immediate upstream node or nodes is called as _______
a) Admission policy
b) Backpressure
c) Forward signaling
d) Backward signaling

Answer: b
Clarification: In this closed loop congestion control technique, the congested node propagates in the opposite direction of the data flow to inform the predecessor node to reduce the flow of packets. This is why this technique is called a node-to-node congestion control technique.

8. Backpressure technique can be applied only to _______
a) Congestion networks
b) Closed circuit networks
c) Open circuit networks
d) Virtual circuit networks

Answer: d
Clarification: In Virtual circuit networks, each node knows the upstream node from which a flow data is coming. So, it makes possible for the congested node to track the source of the congestion and then inform that node to reduce the flow to remove congestion.

9. The packet sent by a node to the source to inform it of congestion is called _______
a) Explicit
b) Discard
c) Choke
d) Backpressure

Answer: c
Clarification: Choke packet is sent by a node to the source to inform it of congestion. Two choke packet techniques can be used for the operation called hop-by-hop choke packet and source choke packet.

10. In the slow-start algorithm, the size of the congestion window increases __________ until it reaches a threshold.
a) exponentially
b) additively
c) multiplicatively
d) suddenly

Answer: a
Clarification: In slow-start algorithm, the size of the congestion window increases exponentially until it reaches a threshold. When it reaches the threshold, it stops increasing and continues sending packets through the threshold window thus preventing congestion.

11. In the congestion avoidance algorithm, the size of the congestion window increases ____________ until congestion is detected.
a) exponentially
b) additively
c) multiplicatively
d) suddenly

Answer: b
Clarification: In the congestion avoidance algorithm, the size of the congestion window increases additively until congestion is detected. Once congestion is detected, the size of congestion window is decreased once and then the packets are transmitted to achieve congestion avoidance.

Computer Networks Multiple Choice Questions on “RIP v1”.

1. Which protocol should you select if the network diameter is more than 17 hops?
a) RIPv1
b) RIPv2
c) EIGRP
d) Both RIPv1 and RIPv2

Answer: a
Clarification: RIP v1 has network diameter is more than 17 hops. It uses classful routing and the routing updates are broadcasted over the network. It notifies routers about the update so that they update their own routing tables.

2. How often does a RIPv1 router broadcast its routing table by default?
a) Every 30 seconds
b) Every 60 seconds
c) Every 90 seconds
d) RIPv1 does not broadcast periodically

Answer: a
Clarification: RIPv1 router broadcasts its routing table every 30 seconds by default. The broadcasted routing table can be used by other routers to find the shortest path among the network devices.

3. Which command displays RIP routing updates?
a) Show IP route
b) Debug IP rip
c) Show protocols
d) Debug IP route

Answer: b
Clarification: The debug IP rip command is used to show the Internet Protocol (IP) Routing Information Protocol (RIP) updates being sent and received on the router. It verifies that the updates are being broadcasted and not multicasted.

4. Two connected routers are configured with RIP routing. What will be the result when a router receives a routing update that contains a higher-cost path to a network already in its routing table?
a) The updated information will be added to the existing routing table Debug IP rip
b) The update will be ignored and no further action will occur Debug IP route
c) The updated information will replace the existing routing table entry
d) The existing routing table entry will be deleted from the routing table and all routers will exchange routing updates to reach convergence

Answer: b
Clarification: When a routing update is received by a router, the router first checks the administrative distance (AD) and always chooses the route with the lowest AD. However, if two routes are received and they both have the same AD, then the router will choose the one route with the lowest metrics, or in RIP’s case, hop count.

5. You type debug IP rip on your router console and see that 172.16.10.0 is being advertised to you with a metric of 16. What does this mean?
a) The route is 16 hops away Debug IP rip
b) The route has a delay of 16 microseconds Debug IP route
c) The route is inaccessible
d) The route is queued at 16 messages a second

Answer: c
Clarification: You cannot have 16 hops on a RIP network by default, because the max default hops possible is 15. If you receive a route advertised with a metric of 16, this means it is inaccessible.

6. Default administrative distance of a static route is ________
a) 0
b) 90
c) 100
d) 1

Answer: d
Clarification: 1 is the default administrative distance of Static Route. It is used by routers to select the best path when there are different routes to the same destination. It’s used only two different routing protocols are being used.

7. Which protocol gives a full route table update every 30 seconds?
a) IEGRP
b) RIP
c) ICMP
d) IP

Answer: b
Clarification: RIP gives a full route table update every 30 seconds. The broadcasted routing table can be used by other routers to find the shortest path among the network devices.

8. _________ is the default administrative distance of RIP.
a) 0
b) 90
c) 120
d) 130

Answer: c
Clarification: The default administrative distance is the default count of numbers assigned to arbitrary routes to a destination. The default administrative distance of RIP is 120. It is used to find the shortest route amongst the number of paths available.

9. Which statement is true regarding classless routing protocol?
a) The use of discontinuous networks is not allowed
b) Use of variable length subnet masks is permitted
c) RIPv1 is a classless routing protocol
d) IGRP supports classes routing within the same autonomous system

Answer: b
Clarification: Use of variable length subnet masks is permitted in classless routing protocols. Also use of discontinuous networks is allowed in such routing protocols. RIPv1 is a classful routing protocol but RIPv2 is classless routing protocol.

10. Where should we use default routing?
a) On stub networks- which have only one exit path out of the network
b) Which have more than one exit path out of the network
c) Minimum five exit paths out of the network
d) Maximum five exit paths out of the network

Answer: a
Clarification: We must use default routing on stub networks. They have only one exit path out of the network, so there can be no specific path decided for such networks.

Computer Networks Multiple Choice Questions on “Physical Layer”.

1. The physical layer is concerned with ___________
a) bit-by-bit delivery
p) process to process delivery
c) application to application delivery
d) port to port delivery

Answer: a
Clarification: Physical layer deals with bit to bit delivery in networking. The data unit in the physical layer is bits. Process to process delivery or the port to port delivery is dealt in the transport layer. The various transmission mediums aid the physical layer in performing its functions.

2. Which transmission media provides the highest transmission speed in a network?
a) coaxial cable
b) twisted pair cable
c) optical fiber
d) electrical cable

Answer: c
Clarification: Fiber optics is considered to have the highest transmission speed among the all mentioned above. The fiber optics transmission runs at 1000Mb/s. It is called as 1000Base-Lx whereas IEEE standard for it is 802.3z. It is popularly used for modern day network connections due to its high transmission rate.

3. Bits can be sent over guided and unguided media as analog signal by ___________
a) digital modulation
b) amplitude modulation
c) frequency modulation
d) phase modulation

Answer: a
Clarification: In analog modulation, digital low frequency baseband signal (digital bit stream) is transmitted over a higher frequency. Whereas in digital modulation the only difference is that the base band signal is of discrete amplitude level. The bits are represented by only two frequency levels, one for high and one for low.

4. The portion of physical layer that interfaces with the media access control sublayer is called ___________
a) physical signalling sublayer
b) physical data sublayer
c) physical address sublayer
d) physical transport sublayer

Answer: a
Clarification: The portion of physical layer that interfaces with the medium access control sublayer is Physical Signaling Sublayer. The main function of this layer is character encoding, reception, decoding and performs optional isolation functions. It handles which media connection the signal should be forwarded to physically.

5. The physical layer provides __________
a) mechanical specifications of electrical connectors and cables
b) electrical specification of transmission line signal level
c) specification for IR over optical fiber
d) all of the mentioned

Answer: d
Clarification: Anything dealing with a network cable or the standards in use – including pins, connectors and the electric current used is dealt in the physical layer (Layer 1). Physical layer deals with bit to bit delivery of the data aided by the various transmission mediums.

6. In asynchronous serial communication the physical layer provides ___________
a) start and stop signalling
b) flow control
c) both start & stop signalling and flow control
d) only start signalling

Answer: c
Clarification: In asynchronous serial communication, the communication is not synchronized by clock signal. Instead of a start and stop signaling and flow control method is followed. Unlike asynchronous serial communication, in synchronous serial communication a clock signal is used for communication, so the start and stop method is not really required.

7. The physical layer is responsible for __________
a) line coding
b) channel coding
c) modulation
d) all of the mentioned

Answer: d
Clarification: The physical layer is responsible for line coding, channel coding and modulation that is needed for the transmission of the information. The physical configuration including pins, connectors and the electric current used is dealt in the physical layer based on the requirement of the network application.

8. The physical layer translates logical communication requests from the ______ into hardware specific operations.
a) data link layer
b) network layer
c) trasnport layer
d) application layer

Answer: a
Clarification: Physical layer accepts data or information from the data link layer and converts it into hardware specific operations so as to transfer the message through physical cables. Some examples of the cables used are optical fiber cables, twisted pair cables and co-axial cables.

9. A single channel is shared by multiple signals by ____________
a) analog modulation
b) digital modulation
c) multiplexing
d) phase modulation

Answer: c
Clarification: In communication and computer networks, the main goal is to share a scarce resource. This is done by multiplexing, where multiple analog or digital signals are combined into one signal over a shared medium. The multiple kinds of signals are designated by the transport layer which is the layer present on a higher level than the physical layer.

10. Wireless transmission of signals can be done via ___________
a) radio waves
b) microwaves
c) infrared
d) all of the mentioned

Answer: d
Clarification: Wireless transmission is carried out by radio waves, microwaves and IR waves. These waves range from 3 Khz to above 300 Ghz and are more suitable for wireless transmission. Radio waves can penetrate through walls and are used in radio communications, microwaves and infrared (IR) waves cannot penetrate through walls and are used for satellite communications and device communications respectively.