Do I Know This Already Chapter 27
Router R1 currently supports IPv4, routing packets in and out all its interfaces. R1's configuration needs to be migrated to support dual-stack operation, routing both IPv4 and IPv6. Which of the following tasks must be performed before the router can also support routing IPv6 packets? (Choose two answers.) a. Enable IPv6 on each interface using an ipv6 address interface subcommand. b. Enable support for both versions with the ip versions 4 6 global command. c. Additionally enable IPv6 routing using the ipv6 unicast-routing global command. d. Migrate to dual-stack routing using the ip routing dual-stack global command.
A (Enable IPv6 on each interface using an ipv6 address interface subcommand.) and C (Additionally enable IPv6 routing using the ipv6 unicast-routing global command.) . Of the four answers, the two correct answers show the minimal required configuration to support IPv6 on a Cisco router: enabling IPv6 routing (ipv6 unicast-routing) and enabling IPv6 on each interface, typically by adding a unicast address to each interface (ipv6 address...). The two incorrect answers list nonexistent commands.
Router R1 has an interface named Gigabit Ethernet 0/1, whose MAC address has been set to 0200.0001.000A. The interface is then configured with the ipv6 address 2001:1:1:1:200:FF:FE01:B/64 interface subcommand; no other ipv6 address commands are configured on the interface. Which of the following answers lists the link-local address used on the interface? a. FE80::FF:FE01:A b. FE80::FF:FE01:B c. FE80::200:FF:FE01:A d. FE80::200:FF:FE01:B
A (FE80::FF:FE01:A) . With an ipv6 address command configured for a global unicast address, but without a link-local address configured with an ipv6 address command, the router calculates its link-local address on the interface based on its MAC address and EUI-64 rules. The first half of the link-local address begins FE80:0000:0000:0000. The router then calculates the second half of the link-local address value by taking the MAC address (0200.0001.000A), injecting FF FE in the middle (0200.00FF.FE01.000A), and flipping the seventh bit (0000.00FF.FE01.000A).
Router R1 has an interface named Gigabit Ethernet 0/1, whose MAC address has been set to 0200.0001.000A. Which of the following commands, added in R1's Gigabit Ethernet 0/1 configuration mode, gives this router's G0/1 interface a unicast IPv6 address of 2001:1:1:1:1:200:1:A, with a /64 prefix length? a. ipv6 address 2001:1:1:1:1:200:1:A/64 b. ipv6 address 2001:1:1:1:1:200:1:A/64 eui-64 c. ipv6 address 2001:1:1:1:1:200:1:A /64 eui-64 d. ipv6 address 2001:1:1:1:1:200:1:A /64 e. None of the other answers are correct.
A (ipv6 address 2001:1:1:1:1:200:1:A/64) . The one correct answer lists the exact same IPv6 address listed in the question, with a /64 prefix length, and no spaces in the syntax of the answer. Another (incorrect) answer is identical, except it leaves a space between the address and prefix length, which is incorrect syntax. The two answers that list the eui-64 parameter both list an address and not a prefix; they should list a prefix to be correct, although neither would have resulted in the IPv6 address listed in the question.
Router R1 has an interface named Gigabit Ethernet 0/1, whose MAC address has been set to 5055.4444.3333. This interface has been configured with the ipv6 address 2000:1:1:1::/64 eui-64 subcommand. What unicast address will this interface use? a. 2000:1:1:1:52FF:FE55:4444:3333 b. 2000:1:1:1:5255:44FF:FE44:3333 c. 2000:1:1:1:5255:4444:33FF:FE33 d. 2000:1:1:1:200:FF:FE00:0
B (2000:1:1:1:5255:44FF:FE44:3333) . With the eui-64 parameter, the router will calculate the interface ID portion of the IPv6 address based on its MAC address. Beginning with 5055.4444.3333, the router injects FF FE in the middle (5055.44FF.FE44.3333). Then, the router inverts the seventh bit in the first byte. Mentally, this converts hex 50 to binary 01010000, changing bit 7 so that the string is 0101 0010, and converting back to hex 52. The final interface ID value is 5255:44FF:FE44:3333. The wrong answers simply list a different value.
Which of the following multicast addresses is defined as the address for sending packets to only the IPv6 routers on the local link? a. FF02::1 b. FF02::2 c. FF02::5 d. FF02::A
B (FF02::2) . FF02::1 is used by all IPv6 hosts on the link, FF02::5 is used by all OSPFv3 routers, and FF02::A is used by all EIGRPv6 routers. FF02::2 is used to send packets to all IPv6 routers on a link.
Router R1 has an interface named Gigabit Ethernet 0/1, whose MAC address has been set to 0200.0001.000A. Which of the following commands, added in R1's Gigabit Ethernet 0/1 configuration mode, results in R1 using a solicited node multicast address of FF02::1:FF00:A? a. ipv6 address 2001:1:1:1:1:200:1:A/64 b. ipv6 address 2001:1:1:1::/64 eui-64 c. ipv6 address 2001:1:1:1::A/64 d. None of the other answers results in R1 using that multicast address.
C (ipv6 address 2001:1:1:1::A/64) . R1 will form the solicited node multicast address by using a format of FF02::1:FFxx:xxxx, replacing xx:xxxx with the last six hex digits of the unicast address. If the link-local address and unicast address have different values in their last six hex digits, the router creates a solicited node multicast for both. To form the solicited node multicast address FF02::1:FF00:A, the last six hex digits of an address must be hex 00:000A. Of three answers that define an IPv6 unicast addresses, only one lists a value whose last six hex digits are 00:000A. Also, in this case, the link-local address will be FE80::FF:FE01:A, resulting in a solicited node multicast address of FF02::1:FF01:A, which is not the address listed in the question.
