CCST Subnetting and CIDR Notation 3

Question 1

The host 192.168.1.130 has a subnet mask of 255.255.255.192. Which network does this host belong to?

Accepted Answer

192.168.1.128

Answer

A /26 mask (255.255.255.192) creates blocks of 64 addresses: .0-.63, .64-.127, .128-.191, .192-.255 — host .130 falls in the 192.168.1.128 subnet.

Question 2

What is the CIDR prefix length for the subnet mask 255.255.252.0?

Accepted Answer

/22

Answer

255.255.252.0 in binary is 11111111.11111111.11111100.00000000, which has 22 consecutive ones, giving a prefix of /22.

Question 3

A network administrator needs subnets from 192.168.5.0/24 that each support exactly 14 usable hosts. Which subnet mask should be used?

Accepted Answer

/28

Answer

A /28 subnet has 4 host bits, providing 2^4-2=14 usable host addresses, which exactly meets the requirement.

Question 4

What is the wildcard mask corresponding to the subnet mask 255.255.255.240?

Accepted Answer

0.0.0.15

Answer

A wildcard mask is the bitwise inverse of the subnet mask; 255 minus 240 equals 15, so the wildcard mask is 0.0.0.15.

Question 5

Which of the following IP addresses falls within the Class B address range?

Accepted Answer

172.16.1.1

Answer

Class B addresses range from 128.0.0.0 to 191.255.255.255; 172.16.1.1 falls within this range.

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