How to use the Subnetting Practice Quiz
- 1. Choose the set10, 20 or 30 questions, and the question types you want.
- 2. Work it outAnswer each question; the working appears straight after.
- 3. Check your scoreSee your score by question type and a full review.
Question types
Questions are generated in your browser from random IPv4 addresses with prefixes from /18 to /30, so you never run out of practice:
- Network address and broadcast address of an IP/prefix.
- Usable hosts in a subnet.
- Subnet mask from CIDR, and CIDR from a mask.
- First and last usable host.
- Splitting a network into smaller equal subnets.
- Same subnet? for two addresses.
- Wildcard masks, as used in Cisco ACLs and OSPF.
Enter a seed number to get the same set again, for example to compare scores with a friend. The answer generator was checked against Python's ipaddress module on 900 generated questions.
Worked example: the block-size method
Take 192.168.10.77/26. A /26 leaves 32 − 26 = 6 host bits, so each block has 2⁶ = 64 addresses, and the mask is 255.255.255.192. Blocks in the last octet start at 0, 64, 128 and 192. 77 falls in the block starting at 64, so:
- Network: 192.168.10.64
- Broadcast: 64 + 64 − 1 = 192.168.10.127
- Usable hosts: 64 − 2 = 62, from 192.168.10.65 to 192.168.10.126
- Wildcard: 0.0.0.63
The calculator under the quiz shows exactly these values for that address, so you can check your working on any IP. Splitting works the same way: dividing a /24 into /27s borrows 3 bits, giving 2³ = 8 subnets of 30 usable hosts each. This is core material for CCNA and for networking questions in placement tests.
Frequently asked questions
Why are /31 and /32 left out?
They are special: /31 is used for point-to-point links with 2 usable addresses (RFC 3021), and /32 is a single host. The calculator handles them, but the quiz sticks to the standard rule.
Does it cover IPv6?
Not yet. All questions are IPv4.
Are classful addresses (A, B, C) tested?
No. Modern networks use CIDR. The calculator still shows the old class for reference.
Is the subnetting practice quiz free to take?
Yes. The subnetting practice quiz lets you answer every question with no form. At your first score screen we ask for your name and WhatsApp number once; after that, the subnetting practice quiz and all other Uncodemy tools stay open.