以前从来没注意过IPv4地址空间内竟然有这么多带有特殊含义的IP地址段……前几天读了RFC3330才知道：
Address Block | Present Use | Reference |
0.0.0.0/8 | "This" Network | [RFC1700, page 4] |
10.0.0.0/8 | Private-Use Networks | [RFC1918] |
14.0.0.0/8 | Public-Data Networks | [RFC1700, page 181] |
24.0.0.0/8 | Cable Television Networks | — |
39.0.0.0/8 | Reserved but subject to allocation | [RFC1797] |
127.0.0.0/8 | Loopback | [RFC1700, page 5] |
128.0.0.0/16 | Reserved but subject to allocation | — |
169.254.0.0/16 | Link Local | — |
172.16.0.0/12 | Private-Use Networks | [RFC1918] |
191.255.0.0/16 | Reserved but subject to allocation | — |
192.0.0.0/24 | Reserved but subject to allocation | — |
192.0.2.0/24 | Test-Net |
|
192.88.99.0/24 | 6to4 Relay Anycast | [RFC3068] |
192.168.0.0/16 | Private-Use Networks | [RFC1918] |
198.18.0.0/15 | Network Interconnect Device Benchmark Testing | [RFC2544] |
223.255.255.0/24 | Reserved but subject to allocation | — |
224.0.0.0/4 | Multicast | [RFC3171] |
240.0.0.0/4 | Reserved for Future Use | [RFC1700, page 4] |