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
/2111111111111111111111100000000000network bitshost bits

How many usable host addresses H are there in an IPv4 subnet with prefix /21?

/21
H =
2.Easy
/2411111111111111111111111100000000network bitshost bits

How many usable host addresses H are there in an IPv4 subnet with prefix /24?

/24
H =
3.Medium
/16 → /2011111111111111111111000000000000network bitshost bits

The network 172.21.0.0/16 is divided into equal subnets with prefix /20. How many subnets N are there?

172.21.0.0/16/20
N =
4.Medium
/24 → /2911111111111111111111111111111000network bitshost bits

The network 192.168.10.0/24 must be divided into at least 30 equal subnets. If you borrow as few bits as possible, how many usable hosts H does each subnet have?

192.168.10.0/2430 subnets
H =
5.Hard
third octet 74 … 78012816403201618041201commonvaries

A router has routes to these networks: 10.135.74.0/24, 10.135.75.0/24, 10.135.76.0/24, 10.135.77.0/24, 10.135.78.0/24. What is the longest prefix length p of a single summary route that covers all of them?

10.135.74.0/24 … 10.135.78.0/24
p =
6.Hard
last octet = 20012806403211608140201networkhost

A host has the address 10.20.92.20/30. What is the last number (fourth octet) x of its subnet's broadcast address?

10.20.92.20/30
x =

Answer key

  1. 1. H = 2046
  2. 2. H = 254
  3. 3. N = 16
  4. 4. H = 6
  5. 5. p = 21
  6. 6. x = 23

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