01 network basics

Catalog

One 、 Test network connectivity

Two 、IP Address Overview

3、 ... and 、 Subnet mask

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One 、 Test network connectivity

1：ifconfig   eth0         View network card information
2：ifconfig         View active interfaces
3：ifconfig   -a         View multiple network interfaces （ Contains hidden interfaces ）
4：ping  IP Address          Test network connectivity
      ping    www.baidu.com
      time=15ms
      ping  167.87.23.4
5：route    -n             View routing table
6：host   The target host /DNS The server         DNS analysis IP Address / domain name （ website ）
    host   172.88.8.35
    host   www.baidu.com
7：ifconfig   Interface    IP Address    Subnet mask
   ifconfig   eth0   192.168.0.1  255.255.255.0
   ifconfig   eth0   192.168.0.1/24
8：ifconfig   Interface   close / open
   ifconfig   eth0  down
   ifconfig   eth0  up
9：ifconfig   Interface : Serial number    IP Address / Mask length          Add virtual interface
   ifconfig  eth0:0  172.88.8.254/24

Two 、IP（IP address） Address Overview

IP Address ： Identify the nodes of a device in the network
IPv4 Address             IPv6 Address
192.168.0.1    
1： form
   32 position 2 It's made up of hexadecimal numbers
   Decimal system ：0 1 2 3 4 5 6 7 8 9 10 11 12    20
   Binary system ：0 1 10 11 100 101 110 111 1000
11000000.10101000.0000000.00000001
2： Representation
dotted decimal
192.168.0.1
3： Hexadecimal conversion
   Decimal system --- Binary system       30（10）---11110（2）
   Binary system --- Decimal system       1101（2）---13（10）
4：0.0.0.0--255.255.255.255
   The first category ： Private address   Public address
   Private address ：
   A:10.0.0.1-10.255.255.254
   B:172.16.0.1-172.31.255.254
   C:192.168.0.1-192.168.255.254
    LAN    Internet

    The second category ：IP First number of addresses

    For general computer networks
    A:0-127                     
    B:128-191                
    C:192-223

    Multicast and special for scientific research               
    D:224-239     Multicast
    E:240-254     scientific research

3、 ... and 、 Subnet mask

1： distinguish IP The network bit and host bit of the address
Default subnet mask
A:255.0.0.0        1+3
B:255.255.0.0        2+2
C:255.255.255.0        3+1
2： How to distinguish between ？
   (1: according to IP Determine the subnet mask corresponding to the address    255.255.255.0
   (2: Determine the network bit and host bit    192.168.0    1
   (3: If two IP The address network bits are the same , So these two IP Belong to the same LAN

Four 、Windows see IP Address

1. Command mode

Windows + R -->   cmd  -->ipconfig

  5、 ... and 、 Gateway concept and DNS Server concept

To configure IP Address ：

1、 Manual configuration  

2、DHCP Automatic access to （ If there are dhcp The server ）

gateway ： Gateway address from one network to another , When it comes to network devices, routers

           The exit address of a network  

           The entry address of a network

DNS The server ： Domain name resolution system , A machine that provides domain name resolution .

Domain name resolution ： Can resolve the domain name to IP Address

www.baidu.com ------->   DNS The server ------->   IP Address  --------> Baidu's servers