Slash notation lookup table

Total-addresses: how many unique addresses can be represented. To determine how many are available to be assigned to devices you need to subtract 2 from the provided number to allow for the ‘network’ and ‘broadcast’ address. A further one of these may need to be assigned to a router.

Net bits Subnet mask Total-addresses
/20 255.255.240.0 4096
/21 255.255.248.0 2048
/22 255.255.252.0 1024
/23 255.255.254.0 512
/24 255.255.255.0 256
/25 255.255.255.128 128
/26 255.255.255.192 64
/27 255.255.255.224 32
/28 255.255.255.240 16
/29 255.255.255.248 8
/30 255.255.255.252 4

eg:  192.168.1.0/25 would include all address between 192.168.1.0 and 192.168.1.127.

eg: 192.168.1.128/25 would include all address between 192.168.1.128 and 192.168.1.255

Write a Reply or Comment

Your email address will not be published.