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
/2111111111111111111111100000000000network bitshost bits

An access list must match the network 172.16.0.0/21. Access lists use a wildcard mask, the inverse of the subnet mask. What is the third octet x of the wildcard mask?

/21
x =
3.Medium
/20 → /2611111111111111111111111111000000network bitshost bits

The network 10.83.176.0/20 is divided into equal subnets with prefix /26. How many subnets N are there?

10.83.176.0/20/26
N =
4.Medium
/24 → /2911111111111111111111111111111000network bitshost bits

The network 192.168.36.0/24 is divided into /29 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 9?

192.168.36.0/24/29subnet 9 (subnet 1 starts at .0)
x =
5.Hard
last octet = 154112806403211618041201networkhost

A host has the address 10.20.174.154/25. What is the fourth octet x of its network address?

10.20.174.154/25
x =
6.Hard
third octet 8 … 13012806403201618040201commonvaries

A router has routes to these networks: 10.170.8.0/24, 10.170.9.0/24, 10.170.10.0/24, 10.170.11.0/24, 10.170.12.0/24, 10.170.13.0/24. What is the longest prefix length p of a single summary route that covers all of them?

10.170.8.0/24 … 10.170.13.0/24
p =

Answer key

  1. 1. H = 2046
  2. 2. x = 7
  3. 3. N = 64
  4. 4. x = 71
  5. 5. x = 128
  6. 6. p = 21

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