1、 Basic questions

How to uniquely identify a computer in the network ？
ip Address .

How can multiple programs on the same computer share the network without conflict ？
Network port .

How can different computer communications understand each other ？
Use the same protocol .

IP Address

●A class IP Address ： from 1 Byte network address and 3 Byte host address composition , The highest bit of the network address must be “0”, Address range 1.0.0.1-126.255.255.254 Usable A Class network consists of 126 individual , Each network can accommodate 1677214 Host computer .

●B class IP Address by 2 Byte network address and 2 Byte host address composition , The highest bit of the network address must be “10”, Address range 128.1.0.1-191.255.255.254 Usable B There are 16384 individual , Every network can hold 65534 host

●C class IP Address by 3 Byte network address and 1 Byte host address composition , The highest bit of the network address must be “110” Range 192.0.1.1-223.255.255.254 C Class network up to 2097152 individual , Every network can hold 254 Host computer

●D class IP Address first Bytes in "1110” Start , It is a special [ ] Reserved address . It doesn't point to a specific network , At present, this kind of address is used in multicast ( Multicast ) The multicast address is used for one-time addressing - - Group computer address range 224.0.0.1-239.255.255.254

● private IP: In so many networks IP in , There is an international regulation part IP The address is used for our lan , That is, it belongs to the private network IP, Not used in the public network , Their scope is :

• 10.0.0.0~ 10.255.255.255
• 172.16.0.0~ 172.31.255.255
• 192.1 68.0.0~ 192.168.255.255

●IP Address 127. 0.0. 1~127 . 255. 255. 255 For loop test
- Such as : 127.0.0.1 On behalf of this machine IP Address , use http://127.0.0.1 You can test the Web The server