IP

IP分段

• A类保留给ZF或大型企业
• B类分配给中等规模的公司
• C类分配给小公司或个人
• D类用于组播
• E类用于实验
• A类地址的第一位总是O，如，10.0.0.1==00001010-00000000-00000000-00000001
• 1.0.0.0-127.255.255.255，默认子网掩码为255.0.0.0，最多可容纳16777215台计算机
• B类地址的前两位总是10，如，172.16.0.1==10101100-00010000-00000000-00000001
• 128.0.0.0-191.255.255.255，默认子网掩码为255.255.0.0，最多可容纳65535台计算机
• C类地址的前三位总是110。如，192.168.0.1==11000000-10101000-00000000-00000001
• 192.0.0.0-223.255.255.255，默认子网掩码是255.255.255.0，最多可容纳254台计算机
• 专用IP地址： 就是我们在3类地址中常见到内网的IP段

前缀 地址段 10.0.0.0/8 10.0.0.0～10.255.255.255 172.16.0.0/12 172.16.0.0～172.31.255.255 192.168.0.0/16 192.168.0.0～192.168.255.255

Special Use IPv4 Addresses

Hosts that do not require access to the Internet can use private addresses

• 10.0.0.0 to 10.255.255.255 (10.0.0.0/8)
• 172.16.0.0 to 172.31.255.255 (172.16.0.0/12)
• 192.168.0.0 to 192.168.255.255 (192.168.0.0/16)

Shared address space addresses: 共享地址空间

• Not globally routable
• Intended only for use in service provider networks
• Address block is 100.64.0.0/10

Others

• Network and Broadcast addresses – within each network the first and last addresses cannot be assigned to hosts
• Loopback address – 127.0.0.1 a special address that hosts use to direct traffic to themselves (addresses 127.0.0.0 to 127.255.255.255 are reserved)
• Link-Local address – 169.254.0.0 to 169.254.255.255 (169.254.0.0/16) addresses can be automatically assigned to the localhost
• TEST-NET addresses – 192.0.2.0 to 192.0.2.255 (192.0.2.0/24) set aside for teaching and learning purposes, used in documentation andnetwork examples
• Experimental addresses – 240.0.0.0 to 255.255.255.254 are listedas reserved
• The range of 224.0.0.0 to 224.0.0.255 is reserved to reach multicast groups on a local network.