5. Internet Addresses
- An internet address is 4 bytes long that consists of network part and host part. The network part identifies a logical network and the host part identifies a machine on that network.
- By convention, each byte is represented by a decimal number. The four decimal numbers are separated by periods. For example, 130.85.99.19
Class 1st Byte Format Comments
- According to how the four bytes are allocated between the network and host parts, internet addresses are divided into several classes.
A 1-126 N.H.H.H Major networks, almost never assigned now
B 128-191 N.N.H.H For large sites; usually subnetted, hard to get
C 192-223 N.N.N.H Easy to get, often obtained in sets
D 224-239 - Multicast addressing (still in development)
E 240-254 - Experimental addresses
- Allocation of IP addresses is centrally managed by interNIC Registration Services, under contract to the National Science Foundation. The interNIC distributes network numbers, and local administrators are responsible for assigning host numbers.