- IPv4 address classes
With an IPv4 IP address, 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, shown in the following table.
| 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. |
- Reserved private IPv4 network ranges
| Name | CIDR block | Address range | Number of addresses | Classful description |
|---|---|---|---|---|
| 24-bit block | 10.0.0.0/8 | 10.0.0.0 – 10.255.255.255 | 16777216 | Single Class A. |
| 20-bit block | 172.16.0.0/12 | 172.16.0.0 – 172.31.255.255 | 1048576 | Contiguous range of 16 Class B blocks. |
| 16-bit block | 192.168.0.0/16 | 192.168.0.0 – 192.168.255.255 | 65536 | Contiguous range of 256 Class C blocks. |
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Subnet Mask
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Loopback
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CIDR
Reference