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Abstract
This document itemizes the potential values for IPv4 subnets. Additional information is provided for Hex and Decmial values, classfull equivalents, and number of addresses available within the indicated block. We appreciate inputs from BrUCe Pinsky (cisco) and Daniel Karrenberg (RIPE).
Table
The following table lists the variable length subnets from 1 to 32, the CIDR representation form and the Decmial equivalents.
Mask value: Hex CIDR Decimal #of add Classfull 80.00.00.00 /1 128.0.0.0 2048 M 128 A C0.00.00.00 /2 192.0.0.0 1024 M 64 A E0.00.00.00 /3 224.0.0.0 512 M 32 A F0.00.00.00 /4 240.0.0.0 256 M 16 A F8.00.00.00 /5 248.0.0.0 128 M 8 A FC.00.00.00 /6 252.0.0.0 64 M 4 A FE.00.00.00 /7 254.0.0.0 32 M 2 A FF.00.00.00 /8 255.0.0.0 16 M 1 A FF.80.00.00 /9 255.128.0.0 8 M 128 B FF.C0.00.00 /10 255.192.0.0 4 M 64 B FF.E0.00.00 /11 255.224.0.0 2 M 32 B FF.F0.00.00 /12 255.240.0.0 1024 K 16 B FF.F8.00.00 /13 255.248.0.0 512 K 8 B FF.FC.00.00 /14 255.252.0.0 256 K 4 B FF.FE.00.00 /15 255.254.0.0 128 K 2 B FF.FF.00.00 /16 255.255.0.0 64 K 1 B FF.FF.80.00 /17 255.255.128.0 32 K 128 C FF.FF.C0.00 /18 255.255.192.0 16 K 64 C
FF.FF.E0.00 /19 255.255.224.0 8 K 32 C FF.FF.F0.00 /20 255.255.240.0 4 K 16 C FF.FF.F8.00 /21 255.255.248.0 2 K 8 C FF.FF.FC.00 /22 255.255.252.0 1 K 4 C FF.FF.FE.00 /23 255.255.254.0 512 2 C FF.FF.FF.00 /24 255.255.255.0 256 1 C FF.FF.FF.80 /25 255.255.255.128 128 FF.FF.FF.C0 /26 255.255.255.192 64 FF.FF.FF.E0 /27 255.255.255.224 32 FF.FF.FF.F0 /28 255.255.255.240 16 FF.FF.FF.F8 /29 255.255.255.248 8 FF.FF.FF.FC /30 255.255.255.252 4 FF.FF.FF.FE /31 255.255.255.254 This space is not usable FF.FF.FF.FF /32 255.255.255.255 This is a single host route
Examples
The following tables illistrate some options for subnet/host partions within selected block sizes.
