IPv4 Subnet Cheat Sheet

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

SUBNETS

CIDR

/32
/31
/30
/29
/28
/27
/26
/25
/24
/23
/22
/21
/20
/19
/18
/17
/16
/15
/14
/13
/12
/11
/10
/9
/8
/7
/6
/5
/4
/3
/2
/1
/0

SUBNET MASK

255.255.255.255
255.255.255.254
255.255.255.252
255.255.255.248
255.255.255.240
255.255.255.224
255.255.255.192
255.255.255.128
255.255.255.0
255.255.254.0
255.255.252.0
255.255.248.0
255.255.240.0
255.255.224.0
255.255.192.0
255.255.128.0
255.255.0.0
255.254.0.0
255.252.0.0
255.248.0.0
255.240.0.0
255.224.0.0
255.192.0.0
255.128.0.0
255.0.0.0
254.0.0.0
252.0.0.0
248.0.0.0
240.0.0.0
224.0.0.0
192.0.0.0
128.0.0.0
0.0.0.0

# OF ADDRESSES

1
2
4
8
16
32
64
128
256
512
1,024
2,048
4,096
8,192
16,384
32,768
65,536
131,072
262,144
524,288
1,048,576
2,097,152
4,194,304
8,388,608
16,777,216
33,554,432
67,108,864
134,217,728
268,435,456
536,870,912
1,073,741,824
2,147,483,648
4,294,967,296

WILDCARD

0.0.0.0
0.0.0.1
0.0.0.3
0.0.0.7
0.0.0.15
0.0.0.31
0.0.0.63
0.0.0.127
0.0.0.255
0.0.1.255
0.0.3.255
0.0.7.255
0.0.15.255
0.0.31.255
0.0.63.255
0.0.127.255
0.0.255.255
0.1.255.255
0.3.255.255
0.7.255.255
0.15.255.255
0.31.255.255
0.63.255.255
0.127.255.255
0.255.255.255
1.255.255.255
3.255.255.255
7.255.255.255
15.255.255.255
31.255.255.255
63.255.255.255
127.255.255.255
255.255.255.255

DECIMAL TO BINARY

SUBNET MASK

255 1111 1111

254 1111 1110

252 1111 1100

248 1111 1000

240 1111 0000

224 1110 0000

192 1100 0000

128 1000 0000

0 0000 0000

WILDCARD

0 0000 0000

1 0000 0001

3 0000 0011

7 0000 0111

15 0000 1111

31 0001 1111

63 0011 1111

127 0111 1111

255 1111 1111

BINARY TO DECIMAL

IP ADDRESS CLASSES

A

B

C

D

E

0.0.0.0 – 127.255.255.255

128.0.0.0 – 191.255.255.255

192.0.0.0 – 223.255.255.255

224.0.0.0 – 239.255.255.255

240.0.0.0 – 255.255.255.255

RESERVED (PRIVATE) RANGES

CLASS A

CLASS B

CLASS C

LOCALHOST

ZEROCONF (APIPA/BONJOUR)

10.0.0.0 – 10.255.255.255

172.16.0.0 – 172.31.255.255

192.168.0.0 – 192.168.255.255

127.0.0.0 – 127.255.255.255

169.254.0.0 – 169.254.255.255

TERMINOLOGY

WILDCARD MASK

CIDR

A wildcard mask indicates which parts of an IP address are available for examination.

Classless interdomain routing was developed to provide more granularity
than legacy classful addressing; CIDR notation is expressed as /XX

Nathan House

Nathan House is the founder and CEO of Station X a cyber security training and consultancy company. He has over 25 years experience in cyber security where he has advised some of largest companies in the world, assuring security on multi-million and multi-billion pound projects. Nathan is the author of the popular "The Complete Cyber Security Course" which has been taken by over half a million students in 195 countries. Winner of the AI "Cyber Security Educator of the Year 2020" award. Over the years he has spoken at a number of security conferences, developed free security tools, and discovered serious security vulnerabilities in leading applications. PGP Fingerprint : CBA3FBF729FB00CB21D64FB00E7955AE6E37FEF1