Subnetting Practice Quiz
Quick drills to sharpen your subnetting. Each question gives you a random IPv4 network and asks for the subnet mask, usable host count, network address, broadcast address, or first usable host. Type your answer, get instant feedback with a short explanation, and build a streak. Great for CCNA prep or just keeping the mental math fast. Nothing is stored and there is no signup.
How to get faster at these
The two facts that unlock most subnetting questions are the powers of two and the "magic number" (256 minus the relevant mask octet). If a question stumps you, do not just guess: open the subnet calculator and step through it, then try a fresh question. Seeing the worked answer a few times beats memorising tables.
If you are still building the fundamentals, start with What is Subnetting? and the subnet cheat sheet, then come back here to test yourself. The CIDR reference has the mask and host count for every prefix if you want to look one up.