IPv4 address category:
I. Composition1. Use a 32-bit address. 2. It is expressed in dotted decimal notation. For example, 172.16.0.0. Each number corresponds to eight binary BITs, which are called a single-bit group (octets ). For example, if the IP address of a host is 128.10.2.1 in binary format, the IP address is 0000000.00001010.00000010.000000013. The address format is: IP address = network address + host address or IP address = Host address + subnet address + host address
Ii. ClassificationTo facilitate addressing and hierarchical network construction, each IP address consists of two ID codes, namely the network ID and host ID. All hosts on the same physical network use the same network ID. A host on the network (including Workstation, server, and router) has a host ID corresponding to it. IP addresses are divided into five types based on different network IDs: Class A address, Class B address, Class C address, Class D address, and Class E address. 1. class A address: the first octet in the four octets represents the network number, the remaining three represent the host bit (a Class a ip address consists of a 1-byte network address and a 3-byte host address ). the range is
0Xxxxxxx, that is, from 0 to 127,
The maximum value of the network address must be "0"The address range is from 1.0.0.0 to 126.0.0.0. There are 126 available class A networks, each of which can accommodate more than 0.1 billion hosts
2. class B address: the first two OCTs represent the network number, the remaining two represent the host bit (a Class B IP address consists of two bytes of network address and two bytes of host address ). the range is
10Xxxxxx, that is, 128 to 191 ,,
The maximum value of the network address must be "10"The address range is 128.0.0.0 to 191.20.255. There are 16382 available class B networks, each of which can accommodate more than 60 thousand hosts
3. class C address: the first three OCTs represent the network number, and the remaining one represents the host bit (a class c ip address consists of a 3-byte network address and a 1-byte host address ). the range is
110XXXXX, that is, 192 to 223 ,,
The maximum value of the network address must be 110". The range is from 192.0.0.0 to 223.20.255. A Class C network can contain more than 2.09 million hosts, and each network can accommodate 254 hosts.
4. Class D address: multicast address in the range of 224 to 239. the first byte of the Class d ip address is
Lll0It is a reserved address. It does not point to a specific network. Currently, this type of address is used in multi-point broadcast (Multicast. A multicast address is used to address a group of computers at a time. It identifies a group of computers that share the same protocol.
5. Class E address:
Llll0"Start, retain the address, used in the experiment, the range is 240 to 255.
3. Private IP AddressTo save IP address space and increase security, some IP address segments are reserved as private IP addresses and will not appear on the Internet. A network with a private IP address is called an intranet or a private network. To communicate with an external network, you must use a Network Address Translation (NAT ).
Private address ranges:
1. In Class A addresses: 10.0.0.0 to 10.20.255.255.255
2. Class B address: 172.16.0.0 to 172.31.255.255
3. Class C address: 192.168.0.0 to 192.168.255.255
4. Some Special IP addresses
The full zero ("0.0.0.0") Address corresponds to the current host. The IP address ("255.255.255.255") of "1" is the broadcast address of the current subnet. 1. IP address 127.0.0.1: local loopback test address.
2. broadcast address: Broadcast bandwidth limit 255
3. IP address 0.0.0.0: represents any network
4. The network number is 0, indicating the network or the CIDR block.
5. All Network numbers are 1: All Networks
6. The host space is 0: represents any host address of a network segment.
7. Host bit: 1 indicates all hosts in the network segment.
5. Description (default subnet and usage)1. Class A address
The expression range of Class A addresses is 0.0.0.0 ~ 126.255.255.255, the default network mask is:
255.0.0.0; Class A addresses are allocated to large networks. In a network, the first group of numbers is used to represent the network address, and the last three groups of numbers are used as the addresses of hosts connected to the network. Assigned to a large network with a large number of hosts (direct individual users) and a small number of local networks. For example, the Network of an IBM company.
2. Class B address
The expression range of Class B address is 128.0.0.0 ~ 191.255.255.255, the default network mask is:
255.255.0.0Class B addresses are allocated to medium-size networks. Class B networks use numbers 1 and 2 to indicate network addresses. The latter two sets of numbers represent the host addresses on the network.
3. Class C address
The expression range of class C address is: 192.0.0.0 ~ 223.00000000255, the default network mask is:
255.255.255.0Class C addresses are allocated to small networks, such as local networks and campus networks. The number of hosts that can be connected is the minimum. Users are managed by dividing them into several network segments. The Class C network uses the first three sets of numbers to represent the network address, and the last set of numbers as the host address on the network.
IP address category
