ICND1 IPv4 and IPv6 4 — Questions and Answers
Question 1: Which command verifies IPv6 connectivity to a remote host from a Cisco router?
- show ipv6 interface
- ping ipv6 2001:DB8::1 (Correct answer)
- traceroute ip 2001:DB8::1
- debug ipv6 packet
Correct answer: ping ipv6 2001:DB8::1
The 'ping ipv6' command (or 'ping 2001:DB8::1') tests end-to-end IPv6 reachability from a Cisco device.
Question 2: What is the total number of bits in an IPv6 address?
- 32
- 64
- 128 (Correct answer)
- 256
Correct answer: 128
IPv6 addresses are 128 bits long, written as eight groups of four hexadecimal digits separated by colons.
Question 3: Which subnet contains the host address 192.168.1.200 with a mask of 255.255.255.224 (/27)?
- 192.168.1.160/27
- 192.168.1.192/27 (Correct answer)
- 192.168.1.192/28
- 192.168.1.224/27
Correct answer: 192.168.1.192/27
A /27 uses blocks of 32: .0, .32, .64, .96, .128, .160, .192; address .200 falls in the .192 block (range .192–.223).
Question 4: What is the IPv6 loopback address?
- ::1 (Correct answer)
- FE80::1
- FF02::1
- 2001::1
Correct answer: ::1
::1 is the IPv6 loopback address (equivalent to 127.0.0.1 in IPv4), used to test the local IPv6 stack.
Question 5: How many subnets are created when a Class C network is subnetted with a /27 mask?
- 4
- 6
- 8 (Correct answer)
- 16
Correct answer: 8
A Class C uses a /24 default; borrowing 3 additional bits for subnetting gives 2^3 = 8 subnets.
Question 6: Which ICMPv6 message type is used by a host to request the link-layer address of another IPv6 node (equivalent to ARP request)?
- Router Advertisement
- Neighbor Advertisement
- Neighbor Solicitation (Correct answer)
- Router Solicitation
Correct answer: Neighbor Solicitation
Neighbor Solicitation (ICMPv6 type 135) is sent to the solicited-node multicast address to resolve an IPv6 address to a MAC address.
Question 7: What range of IPv4 addresses is reserved for APIPA (Automatic Private IP Addressing) when DHCP is unavailable?
- 10.0.0.0 – 10.0.255.255
- 169.254.0.1 – 169.254.255.254 (Correct answer)
- 172.16.0.0 – 172.16.255.255
- 192.168.0.1 – 192.168.0.254
Correct answer: 169.254.0.1 – 169.254.255.254
Windows hosts auto-assign a 169.254.0.0/16 address (APIPA) when they cannot reach a DHCP server.
ICND1 IPv4 and IPv6 4
Which command verifies IPv6 connectivity to a remote host from a Cisco router?