Subnetle: A Daily Subnetting Puzzle

One subnetting puzzle a day, Wordle style. Everyone gets the same puzzle, and a new one appears at midnight UK time. You get six guesses.

How to play

• Read the question: it asks for the network address, broadcast address, first usable host or last usable host of the address shown.
• Type your answer as a normal IPv4 address and press guess.
• Each part of your guess turns green when it’s right. If it isn’t, it tells you whether the real number is higher or lower.
• Two wrong guesses show the subnet mask, and four show the block size. When you’re done, the working is shown step by step.
• Share result copies a little grid of your guesses, with no spoilers. Play a practice one gives you an unlimited random puzzle.

The trick that makes subnetting easy

Find the block size: 256 minus the mask’s value in the octet that isn’t 255 or 0. For a /27 the mask is 255.255.255.224, so the block size is 256 minus 224, which is 32. Subnets then start at 0, 32, 64, 96 and so on. Find the block your address falls in, and the network is its first address, the broadcast is its last, and the usable hosts are everything in between.

When you’d rather not do it in your head, my subnet calculator shows the whole thing. There are more games on the games page.