ICND1 Subnetting 3

Question 1

What is the valid host range for the subnet 172.30.4.0/22?

Accepted Answer

172.30.4.1 – 172.30.7.254

Answer

A /22 block spans 1024 addresses; 172.30.4.0 to 172.30.7.255, so valid hosts are .4.1 through .7.254.

Question 2

Which CIDR prefix provides exactly 510 usable host addresses?

Accepted Answer

/23

Answer

A /23 has 512 total addresses (2^9), minus 2 equals 510 usable hosts.

Question 3

A host has the IP address 10.10.16.55 with a mask of 255.255.252.0. What is its subnet's broadcast address?

Accepted Answer

10.10.19.255

Answer

255.255.252.0 is /22; the block of 4 in the third octet containing 16 is 16–19, so broadcast is 10.10.19.255.

Question 4

In VLSM design, which benefit does it provide over classful subnetting?

Accepted Answer

Allows different subnet sizes within the same network

Answer

VLSM lets you apply different prefix lengths to different subnets, reducing address waste.

Question 5

What is the subnet mask in dotted-decimal notation for /19?

Accepted Answer

255.255.224.0

Answer

/19 sets 19 bits; the third octet has top 3 bits set: 11100000 = 224, giving 255.255.224.0.

(ICND1) Interconnecting Cisco Networking Devices Part 1 Practice Test