Study of information technology

Nowadays, no company, no company can do without the computer equipment, which is equipped with the workplace of each employee.

As a rule, all computers in any office are connected to a computer network. What is a computer network? What does it consist of? On what principle does it work? How to work with it for a simple ordinary employee? Answers to these questions in the article.

Introduction

The network consists of two or more computers connected for the purpose of sharing information and resources. The common network components are shown in the figure below and include the following

  • Server computer;
  • Client computer (workstation);
  • Shared access devices, such as printers (printers);
  • Network devices (switch and router) and media that combine them.

A client is a type of workstation used by one user, for example, a simple computer on a desktop. The server receives requests from client computers for resources, such as files. The computers used as servers are usually located in secure, secure locations and are accessible only to network administrators.

Networks vary in size. Local Area Network (LAN) is usually limited to one room or a group of interconnected rooms. Now every computer can use the LAN.

If a person is working in an office, he or she is likely to be using a computer that is connected to the LAN. Not long ago, a lot of people started setting up LANs at home to share resources between computers.

The Metropolitan Area Net work (MAN) connects users with computer resources within a geographic area. It can also be used to connect two or more LANs.

Computer network protocols

Protocols are rules that describe how clients and servers communicate over the network. There is no single protocol that makes the Internet and the World Wide Web work – there are many protocols with special features.

TCP protocol

The purpose of TCP is to ensure the integrity of network communication. First, TCP splits files and messages into separate parts, called packets. These packets contain information such as destination, source, serial number and checksum values that are used to verify the integrity of the data.

TCP is used together with IP to effectively transfer files over the Internet. IP comes after TCP creates packets using IP addresses to send each packet over the Internet, using the best route at any given time.

When the destination address is reached, TCP verifies the integrity of each packet using a checksum, requests resend if the packet is corrupted, and collects a file or message from multiple packets.

IP Protocol

Working in concert with TCP, IP is a set of rules that control how data is sent between computers on the Internet. The IP directs the packet to the correct address.

Once a packet is sent, it is forwarded to the nearest router (a hardware device designed to manage network traffic) until it arrives at its destination.

Each device connected to the Internet has its own unique IP address. These addresses consist of a set of four numeric groups called octets. The used version of IP, IPv4, uses 32-bit (binary) addressing.

The result is a decimal number in xxx.xxx.xxx.xxx.xxx, where each xxx value is a number from 0 to 255. Theoretically, 4 billion possible IP addresses are available (although many potential addresses are reserved for special needs).

With the rapid growth of mobile devices, even this number of addresses may not be sufficient in the coming years.

IPv6, Internet Protocol Version 6 is the next version of the Internet protocol. IPv6 was developed as an evolutionary set of improvements to the current IPv4 and has backward compatibility with it. Service providers and Internet users can update to IPv6 independently, without having to coordinate with each other.

IPv6 provides more Internet addresses because the values are increased from 32-bit to 128-bit. This means that there are 2128 potential IP addresses. For example, the current Google IP address is 172.217.16.4.

The user can enter these numbers into the web browser address field, press the Enter key, and the Google home page will appear. Of course, it is much easier to print “google.com” (without a space), which is why domain names have been created.

Since it is difficult for people to remember long sequences of numbers, a domain name system has been introduced that links text names to numeric IP addresses.

Top-level domain names with country code

Two-letter country codes are also assigned as top-level domain names. They were originally intended to link the country code of the domain name to the geographical location of the person or organization that registered the name.

In practice, it is quite easy to get a domain name with the code of any country. For example, you can visit the resource r01.ru and many other sites of domain name registrars.