IPv6 Questions and Answers

Answer: A

Correct answer: Router1(config-if)# ipv6 ospf 10 area 0.0.0.0

OSPFv3 is enabled per interface, giving the process ID and the area in one command, so the prompt must be interface configuration mode. It differs from OSPFv2, which is configured under the routing process with network statements - in version 3 the interface command replaces them entirely.

Answer: B

Correct answer: Router1(config-if)# ipv6 router rip 1

RIPng is enabled on the interface with ipv6 router rip followed by the process name or tag. As with OSPFv3, the routing protocol is turned on where the traffic is rather than by listing networks under the process - which is the general pattern for the IPv6 routing protocols.

Answer: B

Correct answer: FF02::9

RIPng uses FF02::9, which is the IPv6 counterpart of the 224.0.0.9 that RIPv2 used. The link-local multicast group is worth learning as a set: FF02::5 and FF02::6 for OSPFv3, FF02::9 for RIPng, and FF02::A for EIGRPv6.

Answer: D

These addresses are meant for nonrouting purposes like link-local, but they are almost globally unique so it is unlikely they will have an address overlap. Unique local addresses were designed as a replacement for site-local addresses.

Answer: D

Adjacencies and next-hop attributes now use link-local addresses, and OSPFv3 still uses multicast traffic to send its updates and acknowledgments with the addresses FF02::5 for OSPF routers and FF02::6 for OSPF designated routers. These are the replacements for 224.0.0.5 and 224.0.0.6, respectively.

Answer: C

Anycast addresses identify multiple interfaces, which is the same as multicast; however, the big difference is that the anycast packet is only delivered to one address, the first one it finds defined in the terms of routing distance. This address can also be called one-to-one-of-many.

Answer: C

Correct answer: 3 and 4

Statements 3 and 4 are correct: IPv4 is 32 bits written as four decimal octets, and IPv6 is 128 bits written as eight groups of four hexadecimal digits. Statement 1 gives IPv6 the length of IPv4, and statement 2 gives it the wrong notation. The move from 32 to 128 bits is a factor of \( 2^{96} \) in address space, not four.

Answer: B

Packets addressed to a multicast address are delivered to all interfaces identified by the multicast address, the same as in IPv4. It is also called a one-to-many address. You can always tell a multicast address in IPv6 because multicast addresses always start with FF.

Answer: A

Correct answer: Packets addressed to a unicast address are delivered to a single interface.

Unicast is the general category, defined by its delivery behaviour: one address, one interface, one recipient. The other three options describe particular *kinds* of unicast address - global, link-local and unique local - so they answer the later questions in this topic rather than this one.

Answer: B

Correct answer: These are your typical publicly routable addresses, just like a regular publicly routable address in IPv4.

A global unicast address is the ordinary routable kind, currently allocated from 2000::/3, and it is the direct equivalent of a public IPv4 address. What distinguishes it from the other unicast types is precisely that it is intended to be routed across the internet.