SUBNET SURVIVOR_
How long can you survive subnetting? Network address, broadcast, host range, CIDR, subnet mask, host counts, and wildcard masks — answer right to keep going, miss and lose a life. Free, no signup, best score saved in your browser.
★ HOW THE MATH WORKS
[ THE BLOCK-SIZE METHOD ]
Block size = 256 − the interesting octet of the mask. The network address is the nearest block boundary at or below the host's octet. Broadcast = next network − 1. Usable hosts = 2^(host bits) − 2. Wildcard mask = 255.255.255.255 − subnet mask.
Modes. Survival gives you three lives at CCNA difficulty. Beginner gives five lives and sticks to /24–/28. Daily 10 is a fixed ten-question set, the same for everyone today.
Want to grind the math first? The full subnetting practice tool grades every field, and the cheat sheet lists every prefix.