TCP/IP: Network Classes
The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. It has also been referred to as the TCP/IP protocol suite, which is named after two of the most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were also the first two networking protocols defined. Class Ranges, Special Ranges and Bit-Wise Representation of TCP/IP Network Classes are stated here for quick reference purposes.
CLASS RANGES
| Class | Leading bits | Start | End | CIDR | Default subnet mask |
|---|---|---|---|---|---|
| Class A | 0 | 0.0.0.0 | 127.255.255.255 | /8 | 255.0.0.0 |
| Class B | 10 | 128.0.0.0 | 191.255.255.255 | /16 | 255.255.0.0 |
| Class C | 110 | 192.0.0.0 | 223.255.255.255 | /24 | 255.255.255.0 |
| Class D (multicast) | 1110 | 224.0.0.0 | 239.255.255.255 | /4 | |
| Class E (reserved) | 1111 | 240.0.0.0 | 255.255.255.255 | /4 |
SPECIAL RANGES
| Addresses | CIDR | Purpose | RFC | Class | Total # of addresses |
|---|---|---|---|---|---|
| 0.0.0.0 - 0.255.255.255 | 0.0.0.0/8 | Zero Addresses | 1700 | A | 16,777,216 |
| 10.0.0.0 - 10.255.255.255 | 10.0.0.0/8 | Private IP addresses | 1918 | A | 16,777,216 |
| 127.0.0.0 - 127.255.255.255 | 127.0.0.0/8 | Localhost Loopback Address | 1700 | A | 16,777,216 |
| 169.254.0.0 - 169.254.255.255 | 169.254.0.0/16 | Zeroconf / APIPA | 3330 | B | 65,536 |
| 172.16.0.0 - 172.31.255.255 | 172.16.0.0/12 | Private IP addresses | 1918 | B | 1,048,576 |
| 192.0.2.0 - 192.0.2.255 | 192.0.2.0/24 | Documentation and Examples | 3330 | C | 256 |
| 192.88.99.0 - 192.88.99.255 | 192.88.99.0/24 | IPv6 to IPv4 relay Anycast | 3068 | C | 256 |
| 192.168.0.0 - 192.168.255.255 | 192.168.0.0/16 | Private IP addresses | 1918 | C | 65,536 |
| 198.18.0.0 - 198.19.255.255 | 198.18.0.0/15 | Network Device Benchmark | 2544 | C | 131,072 |
| 224.0.0.0 - 239.255.255.255 | 224.0.0.0/4 | Multicast | 3171 | D | 268,435,456 |
| 240.0.0.0 - 255.255.255.255 | 240.0.0.0/4 | Reserved | 1700 | E | 268,435,456 |
BIT-WISE REPRESENTATION
- n indicates a binary slot used for network ID
- H indicates a binary slot used for host ID
- X indicates a binary slot (without specified purpose)
Class A
0. 0. 0. 0 = 00000000.00000000.00000000.00000000
127.255.255.255 = 01111111.11111111.11111111.11111111
0nnnnnnn.HHHHHHHH.HHHHHHHH.HHHHHHHH
Class B
128. 0. 0. 0 = 10000000.00000000.00000000.00000000
191.255.255.255 = 10111111.11111111.11111111.11111111
10nnnnnn.nnnnnnnn.HHHHHHHH.HHHHHHHH
Class C
192. 0. 0. 0 = 11000000.00000000.00000000.00000000
223.255.255.255 = 11011111.11111111.11111111.11111111
110nnnnn.nnnnnnnn.nnnnnnnn.HHHHHHHH
Class D
224. 0. 0. 0 = 11100000.00000000.00000000.00000000
239.255.255.255 = 11101111.11111111.11111111.11111111
1110XXXX.XXXXXXXX.XXXXXXXX.XXXXXXXX
Class E
240. 0. 0. 0 = 11110000.00000000.00000000.00000000
255.255.255.255 = 11111111.11111111.11111111.11111111
1111XXXX.XXXXXXXX.XXXXXXXX.XXXXXXXX
Tags: networking, tcp/ip