In the server Intranet 、 Extranet What does that mean? ？

Intranet is also called LAN （Local Area Network,LAN）, It refers to the network composed of multiple computers and network devices in a certain area , For example, campus network 、 Government network, etc , Generally, the area is several kilometers .

Intranet

That is, LAN refers to the computer group interconnected by multiple computers in a certain area . It's usually within a few thousand meters . LAN can realize file management 、 Application software sharing 、 Printer sharing 、 Schedule within the working group 、 E-mail and fax communication services . LAN is closed , It can be made up of two computers in the office , It can also be made up of thousands of computers in a company

What we often call intranet , Literally speaking, it is different from the Internet , In other words, the intranet is generally used for the communication between computers within the LAN , If you need to visit Internet, You need to use the Internet .

The main characteristics of LAN are ：

1、 The geographical coverage is small , Only in a relatively independent local scope

2、 Networking with specially laid transmission media , High data transmission rate （10Mb/s～10Gb/s）;

3、 The communication delay time is short , High reliability ;

4、 LAN can support a variety of transmission media ;

Extranet

Wide area network , Also known as the public network . It is a long-distance network connecting computer communication of LAN or man in different areas . Usually across a large physical range , It covers tens to thousands of kilometers , It can connect multiple regions 、 Cities and countries , Or across several continents and providing long-distance communication , Forming an international remote network . Wan is not the same as Internet .

Two 、 Intranet 、 The difference between the Internet

1、ip The difference between address settings , Generally, Intranet has its own IP Paragraph number , It won't conflict with the Internet segment , The intranet starts from below the router , and IP It's all about 192 At the beginning IP. Generally, you can't have an external network IP Of , Because individuals or small groups using the Internet is also a waste of resources , Therefore, we usually surf the Internet through the intranet , Extranet Ip It's usually used in companies , Schools and other institutions .

2、 A unified exit is needed to connect computers in the intranet to the Internet , May be restricted from some unnecessary access , The external network is a network that can access the Internet without router or switch , Can be directly accessed by the outside world , No need to go through the equipment , Connect directly to the computer .

3、 There will be one more layer of security firewall in the internal network than in the external network （ External network routing ）, Relatively speaking, the ability to resist attacks from external networks will be better ; The disadvantage of Intranet is , May be attacked from within ; Because you want to share bandwidth , The relative network speed may be slower （ The more terminals, the slower ）.

4、 Intranet ip You can change it often , You can define your own rules ; And the Internet ip It's usually fixed , When you install Broadband , Yours ip It's fixed .

3、 ... and 、 Illustration

You have broadband installed in your home , So that multiple people can use the same Broadband , You buy a router , Now , All computers connected to the router 、 Connect the router and put it out wifi On the computer 、 mobile phone , They belong to the same LAN , You check their network connections , You'll find it's all 192 At the beginning ,ip Before 3 The numbers of each network segment are the same , Only the last one is different . These phones 、 Computers use intranet , But if they all go to the website of the Internet , So their external ip Address , It's your broadband ip Address , All mobile phones and computers are the same ip Address , This is the Internet .

Be careful ：

IP In the address , There are three sections of addresses dedicated to private network planning , Connections that cannot be used on the Internet are as follows

NAT technology

NAT Technology converts private addresses into public addresses , So that the host in the Intranet can access the Internet through a small number of public network addresses