Subnetting Practice Generator
Generate random IPv4 subnetting practice questions with answers. Build network, broadcast, host range and host count skills for exams.
Last reviewed by the Radiatus Cloud team
Generate random subnetting questions to practise for CCNA and networking exams.
Need this monitored 24/7?
Radiatus delivers managed cloud & network operations.
Practise subnetting with random questions
Subnetting is a skill that improves with repetition, and this generator produces an endless supply of random practice questions. Each question gives you a random IPv4 address with a random prefix length between /8 and /30, along with the subnet mask, and asks you to work out the network address, the broadcast address, the first and last usable host addresses, and the number of usable hosts. When you are ready, reveal the answer to check your working.
Because the addresses and prefixes are random, you get fresh practice every time rather than memorising a fixed set of examples.
Build exam-ready speed
Networking certifications such as the Cisco CCNA require candidates to subnet quickly and accurately, often without a calculator. Regular timed practice on varied prefixes builds the mental shortcuts needed to find network and broadcast addresses fast. Teachers and students can also use the generator to create worksheets and self-test.
The answers are computed with the same bitwise logic used by real routers, so they are authoritative. Work each question by hand first, then reveal the solution to confirm, which is the most effective way to learn. All generation happens locally in your browser.
Related tools
- Port Scanner — Check which common ports respond on a host and understand what each exposed service means. Scan only systems you are authorised to test.
- DNS Misconfiguration — Analyze DNS records (TXT, SPF) for security gaps.
- TLS Compat Tester — Check client-server compatibility for TLS versions.
- Firewall Rule Risk — Evaluate firewall rules for over-permissive exposure.
Frequently Asked Questions
What does each practice question cover?
Each question asks for the network address, broadcast address, first and last usable host, and the number of usable hosts for a random address and prefix.
What prefix lengths are used?
Prefixes range from /8 to /30, covering the sizes most commonly tested in exams and seen in real networks.
Is this suitable for CCNA preparation?
Yes. The question format and prefix range match what Cisco CCNA and similar certifications expect, making it good timed practice.
How are the answers calculated?
With the same bitwise masking that routers use, so the network, broadcast, host range and host count are authoritative.
Why practise subnetting by hand?
Exams often forbid calculators and reward speed, so building the mental method through repeated practice is essential for passing.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Click to generate a random question, work it out, then reveal the answer.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
Related Tools
Port Scanner
NetworkCheck which common ports respond on a host and understand what each exposed service means. Scan only systems you are authorised to test.
DNS Misconfiguration
NetworkAnalyze DNS records (TXT, SPF) for security gaps.
TLS Compat Tester
NetworkCheck client-server compatibility for TLS versions.