IP address classification (A Class B Class C Class D E class)
IP addresses of four sections, each field is a byte, 8 bits, the maximum value is 255 ,,
IP address consists of two parts, i.e. the network address and host address. That it belongs to the network address of a network to which the Internet, which represents a host address belongs to which host to the network. Both are master-slave relationship.
Four types of the IP address identifies the network in a host. The IPv4 address length is 32 bits, 4 bytes, but in practice we dotted decimal notation.
The IP address of the network number and host number to sub-divided into A, B, C, and three types of special addresses D, E. All-zero and all ones are not retained.
Class A: (1.0.0.0-126.0.0.0) (Default Subnet Mask: 255.0.0.0 or 0xFF000000)
The first byte network number, the three bytes for the host number. Such top IP address is "0", the network address number ranging between 1 to 126.
Generally used for large networks.
Class B: (128.1.0.0-191.255.0.0) (Default Subnet Mask: 255.255.0.0 or 0xFFFF0000)
The first two bytes for the network number, the number of two bytes for the host. Such top IP address is "10", the network address number ranging between 128 to 191.
Generally used for medium-sized networks.
Class C: (192.0.1.0-223.255.255.0) (Subnet Mask: 255.255.255.0 or 0xFFFFFF00)
The first three bytes of the network number, the last byte of a host number. Such top IP address is "110", the network address number ranging between 192 ~ 223.
Generally used for small networks.
Class D: is the multicast address. Such top IP address is "1110", the network address number ranging between 224 to 239. Generally used for multicasting user [1].
Class E: is reserved addresses. Such top IP address is "1111", the network address number ranging between 240 to 255.
Loopback address: 127.0.0.1. Also the address of the machine, the machine is equivalent to localhost or IP.
Generally used for testing. For example: ping 127.0.0.1 to test native TCP / IP is normal.
Now IP network uses 32-bit address in dotted decimal notation, such as 172.16.0.0. Address format is: IP address = address + network host address or IP address of the host address = address + + subnet host address.
IP Address Type
最初设计互联网络时，为了便于寻址以及层次化构造网络，每个IP地址包括两个标识码（ID），即网络ID和主机ID。同一个物理网络上的所有主机都使用同一个网络ID，网络上的一个主机（包括网络上工作站，服务器和路由器等）有一个主机ID与其对应。IP地址根据网络ID的不同分为5种类型，A类地址、B类地址、C类地址、D类地址和E类地址。 1． A类IP地址 一个A类IP地址由1字节的网络地址和3字节主机地址组成，网络地址的最高位必须是“0”， 地址范围从1.0.0.0 到126.0.0.0。可用的A类网络有126个，每个网络能容纳1亿多个主机。 2． B类IP地址 一个B类IP地址由2个字节的网络地址和2个字节的主机地址组成，网络地址的最高位必须是“10”，地址范围从128.0.0.0到191.255.255.255。可用的B类网络有16382个，每个网络能容纳6万多个主机 。 3． C类IP地址 一个C类IP地址由3字节的网络地址和1字节的主机地址组成，网络地址的最高位必须是“110”。范围从192.0.0.0到223.255.255.255。C类网络可达209万余个，每个网络能容纳254个主机。 4． D类地址用于多点广播（Multicast）。 D类IP地址第一个字节以“lll0”开始，它是一个专门保留的地址。它并不指向特定的网络，目前这一类地址被用在多点广播（Multicast）中。多点广播地址用来一次寻址一组计算机，它标识共享同一协议的一组计算机。224.0.0.0到239.255.255.255用于多点广播 。 5． E类IP地址 以“llll0”开始，为将来使用保留。240.0.0.0到255.255.255.254 When the Internet was originally designed, in order to facilitate addressing and network hierarchical structure, each IP address comprises two code (ID), i.e. the network ID and a host ID.
All hosts on the same physical network use the same network ID, a host on the network (including the network workstations, servers, and routers) has a host ID corresponding thereto.
IP addresses are divided into five types, A class address, address Class B, Class C address, a class D address and Class E addresses depending on the network ID.
1. Class A IP address of a class A IP address of a network address and byte 3 byte consisting host address, the network address of the most significant bit must be "0", ranging from 1.0.0.0 to the address 126.0.0.0. A network has available Class 126, each network can accommodate more than 100 million hosts.
2. Class B IP addresses Class B IP address consists of two bytes of network and host addresses composed of 2 bytes, the maximum bit network address must be "10", the address range from 128.0.0.0 to 191.255.255.255. Class B network has the available 16382, each network can accommodate more than 60,000 hosts.
3. Class C IP address of a class C IP address of 3 bytes of network and host addresses composed of 1 byte, the most significant bit network address must be "110." Ranging from 192.0.0.0 to 223.255.255.255. Class C up to 209 million a network, each network can accommodate 254 hosts.
4. Class D addresses are used for multicast (Multicast). Class D IP addresses of the first byte to "lll0" start, which is a special reserved address. It does not refer to a specific network, currently used in this type of address is multicast (Multicast) in. Multicast group address is used to address one computer, it identifies a set of computer share the same protocol. 224.0.0.0 to 239.255.255.255 for multicast.
5. Class E IP addresses "llll0" beginning, reserved for future use. 240.0.0.0 to 255.255.255.254
, 255.255.255.255 broadcast address
全零（“0．0．0．0”）地址对应于当前主机。全“1”的IP地址（“255．255．255．255”）是当前子网的广播地址。
在IP地址3种主要类型里，各保留了3个区域作为私有地址，其地址范围如下： A类地址：10.0.0.0～10.255.255.255 B类地址：172.16.0.0～172.31.255.255 C类地址：192.168.0.0～192.168.255.255 A类地址的第一组数字为1～126。其中0代表任何地址，127为回环测试地址，注意，数字0和 127不作为A类地址，数字127保留给内部回送函数，而数字0则表示该地址是本地宿主机，不能传送。B类地址的第一组数字为128～191。C类地址的第一组数字为192～223。1. A类地址 A类地址的表示范围为：0.0.0.0~126.255.255.255，默认网络掩码为：255.0.0.0；A类地址分配给规模特别大的网络使用。A类网络用第一组数字表示网络本身的地址，后面三组数字作为连接于网络上的主机的地址。分配给具有大量主机（直接个人用户）而局域网络个数较少的大型网络。例如IBM公司的网络。 2. B类地址B类地址的表示范围为：128.0.0.0~191.255.255.255，默认网络掩码为：255.255.0.0；B类地址分配给一般的中型网络。B类网络用第一、二组数字表示网络的地址，后面两组数字代表网络上的主机地址。 3. C类地址 C类地址的表示范围为：192.0.0.0~223.255.255.255，默认网络掩码为：255.255.255.0；C类地址分配给小型网络，如一般的局域网和校园网，它可连接的主机数量是最少的，采用把所属的用户分为若干的网段进行管理。C类网络用前三组数字表示网络的地址，最后一组数字作为网络上的主机地址。 All zeros ( "0.0.0.0") address corresponding to the current host. All "1" of the IP address ( "255.255.255.255") is the current subnet broadcast address.
In the IP address in three main types, each retain the three regions as a private address, the address range is as follows:
Class A addresses: 10.0.0.0 ~ 10.255.255.255
Class B addresses: 172.16.0.0 ~ 172.31.255.255
Class C addresses: 192.168.0.0 ~ 192.168.255.255
Class A first set of numbers 1 to 126 addresses. Wherein 0 represents any address, address 127 for the loopback test, note numbers 0 and not as a Class A address 127, number 127 reserved for internal loopback function, while the number 0 indicates that the address is a local host, can not be transmitted.
The first set of numbers Class B addresses 128 to 191.
The first set of numbers Class C addresses from 192 to 223.
Represents the range of address 1. Class A Class A addresses is: 0.0.0.0 ~ 126.255.255.255, default network mask: 255.0.0.0; A class of particularly large addresses assigned to network usage. A class represents a network address of the network itself, three sets of figures later as an address on a network connected with a first set of digital host. Allocated to a large number of hosts (direct individual users) and less number of large network LAN. For example, a network of IBM Corporation.
2. Class B represents the range of addresses for the Class B addresses: 128.0.0.0 ~ 191.255.255.255, default network mask: 255.255.0.0; Class B addresses assigned to the network medium-sized ships. Class B network address represents a host address on the network behind the two sets of numbers represents the network with the first and second set of numbers.
3. Class C represents the range of addresses to class C address: 192.0.0.0 ~ 223.255.255.255, default network mask: 255.255.255.0; Class C addresses assigned to small networks, such as LAN and campus network in general, it may be connected the minimum number of hosts are used to which the user belongs is divided into several segments management. Class C network with three sets of figures represented by a network address, the last set of numbers as a host address on the network.
In fact, there are Class D and Class E addresses address. But the use of two types of special addresses, here is just a brief introduction: Class D address broadcast address called for a special protocol to send information to the selected node with. Class E addresses are reserved for future use.
