The following function provides an easy way to get the CIDR (Classless Inter Domain Routing) notation for any subnet mask using PowerShell.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 | # Calculate CIDR (Classless Inter Domain Routing) Notation function getCIDRNotationBySubnetmask([string]$subnetmask){ $cidr = 0 $subnetmask.split(".") | foreach { switch($_){ 255 { $cidr += 8 } 254 { $cidr += 7 } 252 { $cidr += 6 } 248 { $cidr += 5 } 240 { $cidr += 4 } 224 { $cidr += 3 } 192 { $cidr += 2 } 128 { $cidr += 1 } default { $cidr += 0 } } } return $cidr } # Examples how to use it getCIDRNotationBySubnetmask 0.0.0.0 getCIDRNotationBySubnetmask 128.0.0.0 getCIDRNotationBySubnetmask 192.0.0.0 getCIDRNotationBySubnetmask 224.0.0.0 getCIDRNotationBySubnetmask 240.0.0.0 getCIDRNotationBySubnetmask 248.0.0.0 getCIDRNotationBySubnetmask 252.0.0.0 getCIDRNotationBySubnetmask 254.0.0.0 getCIDRNotationBySubnetmask 255.0.0.0 getCIDRNotationBySubnetmask 255.128.0.0 getCIDRNotationBySubnetmask 255.192.0.0 getCIDRNotationBySubnetmask 255.224.0.0 getCIDRNotationBySubnetmask 255.240.0.0 getCIDRNotationBySubnetmask 255.248.0.0 getCIDRNotationBySubnetmask 255.252.0.0 getCIDRNotationBySubnetmask 255.254.0.0 getCIDRNotationBySubnetmask 255.255.0.0 getCIDRNotationBySubnetmask 255.255.128.0 getCIDRNotationBySubnetmask 255.255.192.0 getCIDRNotationBySubnetmask 255.255.224.0 getCIDRNotationBySubnetmask 255.255.240.0 getCIDRNotationBySubnetmask 255.255.248.0 getCIDRNotationBySubnetmask 255.255.252.0 getCIDRNotationBySubnetmask 255.255.254.0 getCIDRNotationBySubnetmask 255.255.255.0 getCIDRNotationBySubnetmask 255.255.255.128 getCIDRNotationBySubnetmask 255.255.255.192 getCIDRNotationBySubnetmask 255.255.255.224 getCIDRNotationBySubnetmask 255.255.255.240 getCIDRNotationBySubnetmask 255.255.255.248 getCIDRNotationBySubnetmask 255.255.255.252 getCIDRNotationBySubnetmask 255.255.255.254 getCIDRNotationBySubnetmask 255.255.255.255 |