IP Addressing Cheat Sheet

Welcome to IP Addressing Cheat Sheet. An Internet Protocol address (IP address) is a numerical label such as 192.0.2.1 that is connected to a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: network interface identification, and location addressing.

ADDRESS CLASS: A, B, C

Class:	A	B	C
Range	0-127	128-191	192-223
N/H	N.H.H.H	N.N.H.H	N.N.N.H
Network Bits	Nx8 = 8	Nx8 = 16	Nx8 = 24
Host Bits	Hx8 = 24	W	Hx8 = 8
# Addresses	16,777,210	66,536	256
Private Range	10.0.0.0 – 10.255.25­5.255	172.16.0.0 – 172.31.25­5.255	192.16­8.0.0 – 192.16­8.2­55.255
Subnet Mask	255.0.0.0	255.25­5.0.0	255.25­5.255.0

ADDRESS CLASS: D & E

CLASS	RANGE	NOTE
D	224 – 239	reserved for multic­asting
E	240 – 255	reserved for research & development

Power of 2 table

2^0	1	2^8	256
2^1	2	2^9	512
2^2	4	2^10	1,024
2^3	8	2^11	2,048
2^4	16	2^12	4,096
2^5	32	2^13	8,192
2^6	64	2^14	16,384
2^7	128	2^15	32,768

BIT, VALUE, MASK

BIT	VALUE	N-BITS / H-BITS	MASK
1	128	1 / 7	10000000
2	192	2 / 6	11000000
3	224	3 / 6	11100000
4	240	4 / 4	11110000
5	248	5 / 3	11111000
6	252	6 / 2	11111100
7	254	7 / 1	11111110
8	255	8 / 0	11111111

SOME FORMULAS

# BLOCKS FOR LARGE #s	2^H / 256 = # BLOCKS
NUMBER OF SUBNETS =	2^n ( n = Number of borrowed bits from the host)
NUMBER HOSTS PER SUBNET =	(2^h – 2) ( h = Number of Host bits)

Hosts have always been with the “­-2” part. Because the network address and broadcast address have always been unusable for hosts.

IP Addressing Cheat Sheet