IPv4 subnetting worksheet with answers

Free printable IPv4 subnetting worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
255.255.128.011111111111111111000000000000000network bitshost bits

A subnet has the mask 255.255.128.0. What is its prefix length p?

255.255.128.0
p =
2.Easy
fourth octet of /25112806403201608040201oneszeros

Write the subnet mask of a /25 network in dotted-decimal notation. What is the value x of its fourth octet?

/25
x =
3.Medium
/24 → /2811111111111111111111111111110000network bitshost bits

The network 192.168.116.0/24 is divided into /28 subnets, numbered 1, 2, 3, … from the lowest address (subnet 1 starts at .0). What is the fourth octet x of the broadcast address of subnet 2?

192.168.116.0/24/28subnet 2 (subnet 1 starts at .0)
x =
4.Medium
/?11111111111111111111111000000000network bitshost bits

A department needs 273 host addresses in a single subnet. What is the longest prefix length p (smallest subnet) that is big enough?

273 hosts
p =
5.Hard
last octet = 140112806403201618140201networkhost

A host has the address 10.20.158.140/30. What is the fourth octet x of the last usable host address in its subnet?

10.20.158.140/30
x =
6.Hard
third octet = 37012806413201608140211networkhost

A host has the address 172.20.37.187/20. What is the third octet x of its network address?

172.20.37.187/20
x =

Answer key

  1. 1. p = 17
  2. 2. x = 128
  3. 3. x = 31
  4. 4. p = 23
  5. 5. x = 142
  6. 6. x = 32

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