IPv4 Subnet Cheat Sheet

To supplement the courses in our Cyber Security ​Career Development Platform, here is our IPv4 Subnet Cheat Sheet. 

You may download the PDF version of this cheat sheet here.

Subnets

CIDRSUBNET MASKOF ADDRESSESWILDCARD
/32255.255.255.25510.0.0.0
/31255.255.255.25420.0.0.1
/30255.255.255.25240.0.0.3
/29255.255.255.24880.0.0.7
/28255.255.255.240160.0.0.15
/27255.255.255.224320.0.0.31
/26255.255.255.192640.0.0.63
/25255.255.255.1281280.0.0.127
/24255.255.255.02560.0.0.255
/23255.255.254.05120.0.1.255
/22255.255.252.010240.0.3.255
/21255.255.248.02,0480.0.7.255
/20255.255.240.04,0960.0.15.255
/19255.255.224.08,1920.0.31.255
/18255.255.192.016,3840.0.63.255
/17255.255.128.032,7680.0.127.255
/16255.255.0.065,5360.0.255.255
/15255.254.0.0131,0720.1.255.255
/14255.252.0.0262,1440.3.255.255
/13255.248.0.0524,2880.7.255.255
/12255.240.0.01,048,5760.15.255.255
/11255.224.0.02,097,1520.31.255.255
/10255.192.0.04,194,3040.63.255.255
/9255.128.0.08,388,6080.127.255.255
/8255.0.0.016,777,2160.255.255.255
/7254.0.0.033,554,4321.255.255.255
/6252.0.0.067,108,8643.255.255.255
/5248.0.0.0134,217,7287.255.255.255
/4240.0.0.0268,435,45615.255.255.255
/3224.0.0.0536,870,91231.255.255.255
/2192.0.0.01,073,741,82463.255.255.255
/1128.0.0.02,147,483,648127.255.255.255
/00.0.0.04,294,967,296255.255.255.255

Decimal to Binary

SUBNET MASKWILDCARD
255  1111 11110  0000 0000
254  1111 11101  0000 0001
252  1111 11003  0000 0011
248  1111 10007  0000 0111
240  1111 000015  0000 1111
224  1110 000031  0001 1111
192  1100 000063  0011 1111
128  1000 0000127  0111 1111
0  0000 0000255  1111 1111

Binary to Decimal

IP Address Classes

A0.0.0.0 – 127.255.255.255
B128.0.0.0 – 191.255.255.255
C192.0.0.0 – 223.255.255.255
D224.0.0.0 – 239.255.255.255
E240.0.0.0 – 255.255.255.255

Reserved (Private) Ranges

CLASS A10.0.0.0 – 10.255.255.255
CLASS B172.16.0.0 – 172.31.255.255
CLASS C192.168.0.0 – 192.168.255.255
LOCALHOST127.0.0.0 – 127.255.255.255
ZEROCONF (APIPA/BONJOUR)169.254.0.0 – 169.254.255.255

Terminology

WILDCARD MASKA wildcard mask indicates which parts of an IP address are available for examination.
CIDRClassless interdomain routing was developed to provide more granularity
than legacy classful addressing; CIDR notation is expressed as /XX
CATEGORIES
  • Daniel says:

    Thank you!

  • WAK says:

    You should add RFC 1918 address space to this list

  • Waqas says:

    Thank you Sir.

  • Edwin says:

    Thank you!
    this is very useful.

  • Dai Son says:

    Thank you for sharing useful resources !

  • Alishia says:

    These subnetting masks are really useful for IPv4 addresses.

  • Thomas Kelly says:

    Love this – thank you!

  • Denzil says:

    Thank you very much Nathan. Appreciate that.

  • Will Pape says:

    Thank you! This is a very useful cheatsheet.

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