Subnet mask cheatsheat – how to calculate a CIDR Suffix

This entry was posted by on Thursday, 9 April, 2009 at
Netmask Number IPs Number Hosts
127.0.0.1/32 1 1
127.0.0.1/30 4 2
127.0.0.1/29 8 6
127.0.0.1/28 16 4
127.0.0.1/27 32 30
127.0.0.1/26 64 62
127.0.0.1/25 128 126
127.0.0.1/24 256 254
127.0.0.1/23 512 510
127.0.0.1/16 65.536 65.534

In a nutshell: get the missing part of the /28 to 32 ( It’s 4, right?). 2 4 is the number of IPs (yes, thats 16) , subtract 2 (1 for network 1 for gateway) for the number of usabe hosts (14)

Category: IT
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