Computer Networks Quiz on “Transition from IPV4 to IPV6”.
1. The main reason for transition from IPv4 to IPv6 is _________
a) Huge number of systems on the internet
b) Very low number of system on the internet
c) Providing standard address
d) To provide faster internet
Answer: a
Clarification: Due to huge number of systems on the internet and the lower number of available addresses on IPv4, transition from IPv4 to IPv6 needs to happen. IPv4 provides around 4 billion unique IP addresses whereas IPv6 provides over 340 undecillion unique IP addresses.
2. Which of the following is not a transition strategy?
a) Dual stack
b) Tunneling
c) Conversion
d) Header translation
Answer: c
Clarification: As IPv4 addresses are of 32 bits and IPv6 addresses are of 128 bits, it is not possible to convert IPv4 address to IPv6 address. So, Dual stack, tunneling and header translation are the three strategies which might help in the transition from IPv4 to IPv6.
3. To determine which version to use when sending a packet to a destination, the source host queries which of the following?
a) Dual stack
b) Domain Name Server
c) Header information
d) Transport layer
Answer: b
Clarification: Source host queries DNS to determine which version to use when sending a packet to a destination. The DNS contains both, the IPv4 and IPv6 addresses of the modern dual stack host servers.
4. The strategy used when two computers using IPv6 want to communicate with each other and the packet must pass through a region that uses IPv4 is ______________
a) Dual stack
b) Header translation
c) Conversion
d) Tunneling
Answer: d
Clarification: In tunneling, The IPv4 routers can form a tunnel in which at the sender’s side, the IPv6 datagram is encapsulated in to IPv4, and at the receiver’s side of the tunnel, the IPv4 packet is stripped and the IPv6 packet is sent to the receiver.
5. The correct format of packet in tunnel that uses IPv4 region is ________
i. IPv6 header
ii. Payload
iii. IPv4 header
a) iii-i-ii
b) iii-ii-i
c) i-ii-iii
d) i-iii-ii
Answer: a
Clarification: At the sender’s side, the IPv6 datagram is encapsulated in to IPv4 i.e. An IPv4 header is inserted on top of the IPv6 header, and then the packet is sent through the tunnel.
6. ___________ is necessary when the sender wants to use IPv6, but the receiver does not understand IPv6.
a) Dual stack
b) Header translation
c) Conversion
d) Tunneling
Answer: b
Clarification: Header translation is used when the sender wants to use IPv6, but the receiver does not understand IPv6. It is made possible through a Network Address Translation – Protocol Translation enabled device such as a gateway.
7. Header translation uses ___________ to translate an IPv6 address to an IPv4 address.
a) IP address
b) Physical address
c) Mapped address
d) MAC address
Answer: c
Clarification: A mapped IPv6 address contains the IPv4 address in its last 32-bits and is preceded by 16 1s and 80 0s. It can be used to translate an IPv6 address to an IPv4 address.
8. Which of the following is not a step in the Header translation procedure?
a) The IPv6 mapped address is changed to an IPv4 address by extracting the rightmost 32bits
b) The value of the IPv6 priority field is discarded
c) The type of service field in IPv4 is set to zero
d) The IPv6 flow label is considered
Answer: d
Clarification: In the header translation procedure, first the IPv6 mapped address is changed to an IPv4 address by extracting the rightmost 32bits, then the value of the IPv6 priority field is discarded, and finally the ToS field in the IPv4 header is set to zero. IPv6 flow label is ignored in the procedure.