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IP address classes

IP (Internet protocol) is a Network Layer protocol (Layer 3) that considered ‘routed’ protocol. It addresses the Network Packets so that routing protocols like OSPF,BGP and RIP can correctly route the packet.

IP defines the IP addresses. IP address is a 32 bit number (4 octets). It comprises of Network and Host numbers. The higher order bits define the Network number as shown below.

There are 5 classes of IP addresses:

 

 

Class

Leading bits

Size of network
Number bit field

Size of rest bit field

Number of Networks

Addresses Per Network

Start address

End address

A

0

8

24

128 (27)

16,777,216 (224)

0.0.0.0

127.255.255.255

B

10

16

16

16,384 (214)

65,536 (216)

128.0.0.0

191.255.255.255

C

110

24

8

2,097,152 (221)

256 (28)

192.0.0.0

223.255.255.255


 

             

Class D is defined as Multicast. Address Range: 224 – 239

Class E is experimental. Address Range: 240 – 254

 

127.0.0.1 to 127.255.255.255 is defined as loop back address range.

 

Also, a range of IP addresses are reserved for Private use (i.e not routable in internet). They are

 

Class A

10.0.0.0 – 10.255.255.255

Class B

172.16.0.0 – 172.31.0.0

Class C

192.168.0.0 – 192.168.255.255

 

IPV6 uses 128 bit addresses and primarily introduced to address the depleting IPV4 addresses.

             
               
               

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