Cisco CCNA IPv4 and IPv6 Addressing Questions and Answers

Question 1

A network is configured with the address 192.168.100.0/28. How many usable host IP addresses are available on this network?

Accepted Answer

14

Answer

The /28 prefix leaves 4 bits for the host portion of the address (32 total bits - 28 network bits = 4 host bits). The total number of addresses in the subnet is 2^4, which equals 16. However, two addresses in every subnet are reserved: the first address for the network ID and the last address for the broadcast address. Therefore, the number of usable host addresses is 16 - 2 = 14.

Question 2

Which of the following is the correct compressed version of the IPv6 address FE80:0000:0000:0000:02AA:00FF:FE9A:4CA2?

Accepted Answer

FE80::2AA:FF:FE9A:4CA2

Answer

IPv6 compression rules allow for two main actions: omitting leading zeros within each hextet, and replacing one (and only one) contiguous block of all-zero hextets with a double colon (::). In FE80:0000:0000:0000:02AA:00FF:FE9A:4CA2, the three consecutive '0000' hextets can be replaced by '::', and the leading zeros in '02AA' and '00FF' can be removed, resulting in FE80::2AA:FF:FE9A:4CA2.

Question 3

A network technician is reviewing IP configurations on a local area network. Which of the following IP addresses is a valid RFC 1918 private address?

Accepted Answer

10.1.1.25

Answer

RFC 1918 defines specific address ranges for use in private, non-routable networks. These ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. The address 10.1.1.25 falls within the 10.0.0.0/8 range. 169.254.50.100 is an APIPA address, while the other options are public IP addresses.

Question 4

A network interface card has the MAC address A8:BB:C1:12:34:56. If this interface autoconfigures its IPv6 interface ID using the EUI-64 process, what will the resulting interface ID be?

Accepted Answer

AABB:C1FF:FE12:3456

Answer

The EUI-64 process converts a 48-bit MAC address into a 64-bit interface ID. First, 'FFFE' is inserted in the middle of the MAC address (A8BB:C1FF:FE12:3456). Second, the seventh bit (the Universal/Local or U/L bit) of the first byte is flipped. The first byte A8 is '10101000' in binary. Flipping the seventh bit results in '10101010', which is 'AA' in hexadecimal. This yields the final interface ID of AABB:C1FF:FE12:3456.

Question 5

A network administrator is configuring a new web server. The network address is 172.16.32.0/22. Which of the following IP addresses can be validly assigned to the server?

Accepted Answer

172.16.35.100

Answer

The /22 CIDR notation corresponds to a subnet mask of 255.255.252.0. This creates a network range from 172.16.32.0 to 172.16.35.255. The first address (.32.0) is the network ID, and the last address (.35.255) is the broadcast address, neither of which can be assigned to a host. Therefore, 172.16.35.100 is a valid, usable host address within this range.

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Cisco CCNA IPv4 and IPv6 Addressing Questions and Answers