mikecathey.com


IP addressing


What is an IP address (IPV4)?


Decimal Equivalents of Bit Patterns
128
|
\/
64
|
\/
32
|
\/
16
|
\/
8
|
\/
4
|
\/
2
|
\/
1
|
\/
0 0 0 0 0 0 0 0 = 0
1 0 0 0 0 0 0 0 = 128
1 1 0 0 0 0 0 0 = 192
1 1 1 0 0 0 0 0 = 224
1 1 1 1 0 0 0 0 = 240
1 1 1 1 1 0 0 0 = 248
1 1 1 1 1 1 0 0 = 252
1 1 1 1 1 1 1 0 = 254
1 1 1 1 1 1 1 1 = 255


Distinguishing IP Address Classes
Class Top Octet Range Top Octet Binary Network . Host
A 0.X.X.X- 127.X.X.X 0xxxxxxx NNN.HHH.HHH.HHH
B 128.X.X.X - 191.X.X.X 10xxxxxx NNN.NNN.HHH.HHH
C 192.X.X.X - 223.X.X.X 110xxxxx NNN.NNN.NNN.HHH
D 224.X.X.X - 239.X.X.X 1110xxxx NNN.NNN.NNN.HHH

Where N = Network Address space and H = Host Address space
Where 'Top Octet Bits' = Decimal Equivalent Bits


Private IP Addresses
See
RFC1918
Private IP address space
Network Netmask CIDR
10.0.0.0 10.255.255.255 10.0.0.0/8
172.16.0.0 172.31.255.255 172.16.0.0/12
192.168.0.0 192.168.255.255 192.168.0.0/16


CIDR -- Classless InterDomain Routing

Masks Listed by Number of Bits
Network
ID Bits
Host ID Bits Subnet Example Notation # of Subnets # of Hosts on
Each Subnet

24

8

.0

192.168.1.1/24

1

254

25

7

.128

192.168.1.1/25

2

126

26

6

.192

192.168.1.1/26

4

62

27

5

.224

192.168.1.1/27

8

30

28

4

.240

192.168.1.1/28

16

14

29

3

.248

192.168.1.1/29

32

6

30

2

.252

192.168.1.1/30

64

2


Glossary -- coming soon!


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