ICND1 Subnetting 2

Question 1

How many usable host addresses are available in a /27 subnet?

Accepted Answer

30

Answer

A /27 subnet has 32 total addresses (2^5), minus 2 for network and broadcast, leaving 30 usable hosts.

Question 2

What is the broadcast address for the network 192.168.10.64/26?

Accepted Answer

192.168.10.127

Answer

A /26 block is 64 addresses; starting at .64, the broadcast is .64 + 63 = .127.

Question 3

Which subnet mask corresponds to the CIDR notation /20?

Accepted Answer

255.255.240.0

Answer

/20 means 20 bits are set, so the third octet has the top 4 bits set: 11110000 = 240, giving 255.255.240.0.

Question 4

A network administrator needs at least 50 subnets from 172.16.0.0/16. What is the minimum number of bits to borrow from the host portion?

Accepted Answer

6

Answer

2^6 = 64 subnets, which satisfies the requirement of at least 50; 2^5 = 32 is insufficient.

Question 5

What is the network address for the host IP 10.4.77.130/25?

Accepted Answer

10.4.77.128

Answer

A /25 mask is 255.255.255.128; ANDing 130 with 128 gives 128, so the network is 10.4.77.128.

(ICND1) Interconnecting Cisco Networking Devices Part 1 Practice Test