IP Classes

Short for Internet Protocol, IP is an address of a computer or other network device on a network using IP or TCP/IP . For example, the number "166.70.10.23" is an example of such an address. These addresses are similar to addresses used on houses and help data reach its appropriate destination on a network.

There are five classes of available IP ranges: Class A, Class B, Class C, Class D and Class E, while only A, B and C are commonly used. Each class allows for a range of valid IP addresses. Below is a listing of these addresses.

Class	Address Range	Supports
Class A	1.0.0.1 to 126.255.255.254	Supports 16 million hosts on each of 127 networks.
Class B	128.1.0.1 to 191.255.255.254	Supports 65,000 hosts on each of 16,000 networks.
Class C	192.0.1.1 to 223.255.254.254	Supports 254 hosts on each of 2 million networks.
Class D	224.0.0.0 to 239.255.255.255	Reserved for multicast groups.
Class E	240.0.0.0 to 254.255.255.254	Reserved for future use, or Research and Development Purposes.

Ranges 127.x.x.x are reserved for loopback tests, for example, 127.0.0.1. Ranges 255.255.255.255 are used to broadcast to all hosts on the local network.

All IP addresses are broken down into 4 sets of octets that break down into binary to represent the actual IP address. The below chart is a basic example of the basic IP 255.255.255.255.

IP:	255.	255.	255.	255.
Binary value:	11111111.	11111111.	11111111.	11111111.
Octet value:	8	8	8	8

If we were to break down the IP "166.70.10.23", which is the IP address of Computer Hope, you would get the below value.

166.	70.	10.	23
10100110.	01000110.	00001010.	00010111
128+32+4+2=166	64+4+2=70	8+2=10	16+4+2+1=23

There are several IP addresses used or automatically assigned on a network. For example:

166.70.10.0	0 is the automatically assigned network address.
166.70.10.1	1 is the commonly used address used as the gateway.
166.70.10.2	2 is also a commonly used address used for a gateway.
166.70.10.255	255 is automatically assigned on most networks as the broadcast address.

Users and/or companies who need to register an IP address or a valid range of IP addresses must register that IP address through InterNIC.

• Click here to see what your IP address is and other system settings are.
• Additional information about network commands used to determine network information can be found on document CH000444.
• Additional information about how to determine an IP address can be found on document CH000483.
• See document CH000962 for additional information about determining another computer or a website IP address.
• Information about how to find the physical location of an IP address can be found on document CH001044.