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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Name: ____________________   Date: ____________

1.Easy
255.255.224.011111111111111111110000000000000network bitshost bits

A subnet has the mask 255.255.224.0. What is its prefix length p?

255.255.224.0
p =
2.Easy
third octet of /19112816413201608040201oneszeros

Write the subnet mask of a /19 network in dotted-decimal notation. What is the value x of its third octet?

/19
x =
3.Medium
/?11111111111111111111110000000000network bitshost bits

A department needs 839 host addresses in a single subnet. What is the longest prefix length p (smallest subnet) that is big enough?

839 hosts
p =
4.Medium
/24 → /2511111111111111111111111110000000network bitshost bits

The network 192.168.78.0/24 is divided into /25 subnets, numbered 1, 2, 3, … from the lowest address (subnet 1 starts at .0). What is the fourth octet x of the network address of subnet 2?

192.168.78.0/24/25subnet 2 (subnet 1 starts at .0)
x =
5.Hard
third octet 15 … 20012806403201618141211commonvaries

A router has routes to these networks: 10.234.15.0/24, 10.234.16.0/24, 10.234.17.0/24, 10.234.18.0/24, 10.234.19.0/24, 10.234.20.0/24. What is the longest prefix length p of a single summary route that covers all of them?

10.234.15.0/24 … 10.234.20.0/24
p =
6.Hard
third octet 47 … 48012806413201618141211commonvaries

A router has routes to these networks: 10.247.47.0/24, 10.247.48.0/24. What is the longest prefix length p of a single summary route that covers all of them?

10.247.47.0/24 … 10.247.48.0/24
p =

Answer key

  1. 1. p = 19
  2. 2. x = 224
  3. 3. p = 22
  4. 4. x = 128
  5. 5. p = 19
  6. 6. p = 19

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