Free tool
Enter an IPv4 address and a prefix length to get the subnet mask, network address, broadcast address, host range and address count, worked the way networking questions on IT certification exams expect.
Built for Security+ and networking exam prepThe number after the slash, as in /26.
Enter a valid IPv4 address and a prefix from 0 to 32.
Subnetting shows up in networking and security exams. Encodr turns the method into spaced-repetition practice so it holds until exam day.
Get started freeA prefix length such as /26 says how many of the 32 address bits are the network part. The
remaining bits are the host part, so the subnet holds 2^(32 - prefix) addresses. A /26
leaves 6 host bits, which is 64 addresses.
The network address is the first address in the block (all host bits 0) and the broadcast address is the last (all host bits 1). On ordinary subnets those two are not assignable to hosts, so the usable count is the total minus 2. Worked example: 192.168.10.77/26 sits in the block 192.168.10.64 to 192.168.10.127, with 62 usable hosts from .65 to .126.
Two edge cases: a /31 has two addresses and both are usable on point-to-point links (RFC 3021), and a /32 is a single host address. This tool applies those two special cases.
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