Shulou(Shulou.com)06/01 Report--

In this century, the vast majority of computers are in one form of network or another. If the computer cannot be connected to the Internet, then it is just a piece of scrap iron and can do nothing. A Network means that two or more computers are connected by protocol (through HTTP,FTP,HTTPS, etc.). Services can then be provided to those in need in this way.

The network is a huge object and is constantly expanding. It is the most frequently mentioned interview topic. Network questions are the same for all people who need an interview, whether they are system administrators, programmers, or branches in the field of information technology. This also shows the needs of the market, everyone should have the basic knowledge of the network.

Here I try to list 7 basic interview questions about the Internet and their answers.

1. What is a computer network?

A: a computer network connects two or more nodes through a physical medium, such as cable or wireless, to exchange data on preconfigured services or protocols. Computer network is the result of a multidisciplinary role-electrical engineering, computer science, communications, computer engineering, information technology related to their theoretical and practical results. The most widely used computer network today is the Internet, which supports the WWW.

2. What is DNS?

Answer: representative of DNS (Domain NameSystem). It is the name system for all resources on the Internet, including physical nodes and applications. DNS is a way to locate network resources, and it is an indispensable component on the Internet.

Normally, it is easy to remember xyz.com, but it is not easy to remember the IPv4 address 82.175.219.112. When you use IPv6, things get worse. Now if you think about it, you want to list the 10 most frequently visited resources on the web. Science has proved that humans are better at remembering names than numbers.

The function of DNS is to match the domain name to a consistent IP address, and it works under a hierarchical structure.

3. What are IPv4 and IPv6? Who is managing them?

IPv4 and IPv6 are Internet protocols that represent version 4 and version 6, respectively. The IP address is a unique representation of a device on the network. All Internet devices must have a unique legal address to work properly.

IPv4 is a 32-bit number that represents a device on the network and is by far the most widely used. It supports 4.2 billion unique IP addresses, but seeing the growing number of devices connected to the Internet, a better version of IP addresses is needed to support more users. So IPv6 appeared. An example of IPv4 is

82.175.219.112

IPv6 is a 128-bit number that represents devices on the network. It supports 340 trillion unique IP addresses. This is enough for each person to have a million addresses. Enough for all the equipment of this century. With the invention of IPv6, we no longer need to worry about the lack of IP addresses. An example of IPv6 is

2005:3200:230:7e:35dl:2874:2190

4. Make a brief introduction to PAN,LAN,HAN,SAN,CAN,MAN,WAN,GAN.

A: PAN is personal areanetwork. It is a connection between computers and devices that are very close to people. Computer, telephone, fax, printer and so on. The range is limited to 10 meters.

LAN is Local Area Network. LAN is a small geographical area of device interconnection. Offices, schools, hospitals and so on. A LAN can connect to the WAN through a gateway.

HAN stands for House Area Network. HAN is the LAN of the home, but the devices connected to the home include personal computers, telephones, faxes, printers and so on.

SAN stands for Storage Area Network,SAN is the connection between different storage devices, but these storage devices look as if they are local.

CAN stands for Campus Area Network,CAN, which is a network that connects devices, printers, telephones and auxiliary devices on campus. It connects dormitory buildings and other institutions in a university.

MAN (MetropolitanArea Network) metropolitan area network, MAN connects devices that cover large geographical areas. From one city to another.

WAN (WideArea Network), connected to devices, telephones, printers, scanners, etc. Covering every geographical location, it can connect cities, countries, and even continents.

GAN (GlobalArea Network). Connected to mobile phones using satellites around the world.

5. What is POP3?

A: POP3 stands for Post Office Protocol version 3 (Postoffice Protocol3). POP3 is a protocol that listens on port 110and is responsible for accessing mail services on client machines. POP3 works in two modes, delete mode and hold mode.

Delete mode: a message is deleted after it is successfully retrieved in the mailbox.

Keep mode: the mail in the mailbox remains intact after successful retrieval.

6. What is the standard for checking network availability?

A: network availability is measured by the following factors

Downtime (Downtime): the time it takes for the network to return to normal

Failure frequency (Failure Frequency): how often it fails when it needs to work.

7. What is a router?

A: a router is a physical device that acts as a gateway and connects two networks. It forwards packets containing data / information from one network to another. It is responsible for the interconnection between the two networks.

That's about it.

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