Appendix C. Lists of Reserved Ports, ICMP Types and Codes, and Internet Protocols
The second table shows the IP address interval for each class.
Mask | IP address class | |
0 | 0.0.0.0 | 0 |
1 | 128.0.0.0 | 1 |
2 | 192.0.0.0 | 2 |
3 | 224.0.0.0 | 3 |
4 | 240.0.0.0 | 4 |
5 | 248.0.0.0 | 5 |
6 | 252.0.0.0 | 6 |
7 | 254.0.0.0 | 7 |
8 | 255.0.0.0 | 0 |
9 | 255.128.0.0 | 1 |
10 | 255.192.0.0 | 2 |
11 | 255.224.0.0 | 3 |
12 | 255.240.0.0 | 4 |
13 | 255.248.0.0 | 5 |
14 | 255.252.0.0 | 6 |
15 | 255.254.0.0 | 7 |
16 | 255.255.0.0 | 0 |
17 | 255.255.128.0 | 1 |
18 | 255.255.192.0 | 2 |
19 | 255.255.224.0 | 3 |
20 | 255.255.240.0 | 4 |
21 | 255.255.248.0 | 5 |
22 | 255.255.252.0 | 6 |
23 | 255.255.254.0 | 7 |
24 | 255.255.255.0 | 0 |
25 | 255.255.255.128 | 1 |
26 | 255.255.255.192 | 2 |
27 | 255.255.255.224 | 3 |
28 | 255.255.255.240 | 4 |
29 | 255.255.255.248 | 5 |
30 | 255.255.255.252 | 6 |
31 | 255.255.255.254 | 7 |
32 | 255.255.255.255 | 8 |
Example: We want to split the network 130.234.250.0/25 (i.e., 130.234.250.0- 130.234.250.127) into four subnets. The netmask for each subnet will be 27 bits, which means 255.255.255.224. This netmask is in IP class 3. The second table gives us the following available intervals:
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