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Related concepts of 1.1IP address

The following picture can be seen in the dialog window configured by the computer networking protocol:

We can find that there are two options in its properties: automatic but manual modification. Let's briefly explain the above nouns.

IP address: the network layer is responsible for defining the data through which data flows through the network. What we usually see is 192.168.XXX.XXX.

Subnet mask: a bitmask used to indicate which bits of an IP address identify the subnet in which the host resides and which bits identify the host.

Default gateway: if a host cannot find an available gateway, it sends the packet to the default designated gateway, which processes the packet.

DNS server: a server that translates domain names (domain name) and corresponding IP addresses (IP address).

This article mainly introduces the basic knowledge of IP address. First of all, the IP address is the network layer that belongs to the TCP/IP suite. The IP protocol consists of the following four protocols: ICMP, IGMP, ARP and RARP. The example of 192.168.XXX.XXX cited above is to use dotted decimal to represent IP addresses. In fact, IP addresses (IPv4) are 32-bit binary in a computer. You can refer to another blog post on binary conversion methods:

Quick calculation of binary conversion (0,255)

Classification of 1.2IP addresses 1.2.1 Classification by component

The IP address is composed of the network part and the host part, which is divided into the following five parts, among which A | B | C has more applications.

1.2.2 Classification according to particularity

According to the particularity of IP address, it can be divided into public address and private address. First, let's introduce the private address:

In fact, the private address consists of three parts:

Among the class B addresses, 169.254.0.0 to 169.254.255.255 are reserved addresses. If your IP address obtains the IP address automatically and you do not find an available DHCP server on the network, you will get a temporary IP address from 169.254.0.1 to 169.254.255.254.

Now that you have a range of private addresses, the rest (except 0.0.0.0 and 255.255.255.255) are public network addresses!

1.3Introduces ping tools and ipconfig commands (Windows)

First, introduce the ipconfig command:

Ipconfig: view Nic summary information, IP address, subnet mask, default gateway; ipconfig / all: view details, MAC address, etc.; ipconfig / release: release address; ipconfig / renew: re-obtain address.

In addition, ping, to be exact, ping is also a command, and the help manual can be found through man ping in Linux.

Ping is based on ICMP (Network Control Information Protocol). The basic command is ping ip address. Generally, we use it to detect whether the network is unobstructed or not.

Interworking with other hosts. Unobstructed will return relevant information (byte size, which can be set by adding-l byte size at the end of the command; delay time, one

General is ms level; TTL (time to live): the maximum life cycle that a packet can go through in network transmission). Conversely, there are two situations: request timeout: a packet that indicates that it is connected but has not received a response from the other party cannot reach the target host: it indicates that the other host cannot be connected, and the packet cannot be sent to the destination host.

You can add parameters after ping:

-t: four packets are sent by default if it is not added, and-t means it will be sent all the time.

-a: returns the host name of the other party

-l: change the byte size.

Finally, a ping test flow is given:

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