2. List 3 basic network topologies:

Write down the answer: __________________________________________

3. Select the transmission speed of the medium speed network.

1) up to 100Mbps

2) up to 100MB/s

3) up to 1000Mbps

4. The global network is.

1. connected system local networks

2. A system of interconnected computers

3. system of interconnected local telecommunication networks

4. system interconnected local networks and computers of individual users

5. To connect two computers via telephone lines, you must have:

1. Modem

2. two modems

3. telephone, modem and special software

4. by modem on each computer and special software

6. Which of the following schemes for connecting computers is a closed chain?

1. Tire

2. Ring

3. Star

4. There is no right answer

7. Which cable provides data transfer rates up to 10 Mbps?

1. Coaxial

2. twisted pair

3. optical fiber

4. there is no correct answer

8. The largest network size (up to 20 km) has a topology:

Star

Ring

Tire

9. The smallest network size (up to 200 m) has a topology:

Star

Ring

Tire

10. The topology of a computer network in which all computers in the network are connected to a central node is called

1. Tire

2. Ring

3. Star

4. There is no right answer

11. Protocol is

1. the ability of a computer to send files through information transfer channels

2. LAN device

3.Computer network communication standard

4. standard for sending messages via e-mail

12. The highest level of security

Star

Ring

Tire

13. For general access of network users, use:

1) work station

2) server

3) client

14. Multiport devices to connect a PC with a network cable?

Write down the answer: __________________________________________

15. Communication channel providing high-speed transmission?

Write down the answer: __________________________________________

16. A computer that uses server resources is called ...

Write down the answer: __________________________________________

17. Data on the network is transmitted in packets no larger than:

1.5 GB

1.5 Kb

1.5 bytes

18. Types of computer networks:

Personal, local, corporate, territorial, global

Personal, local, corporate, city, global

Personal, satellite, 4-G

19. Communication lines are of two types:

Satellite and Glonass

Wireless and global

Wireless and wired

20. Bluetooth operates within a radius

10 meters 2) 20-30 meters 3) 100 meters

21. LAN maximum can connect

1000 computers

100 computers

20 computers

22. An eight-pin connector with a latch for connecting a PC to a network:

COM 2. RJ-48 3. RJ-45

23 Switches or switches used for:

to choose a route

combining computers into a single network

signal amplification

24. The bandwidth of the information channel is measured:

1.Hertz 2.Seconds 3.Mbps

25. The lowest bandwidth and noise immunity has:

Coaxial cable

Telephone cable 3.Twisted pair

Answers

Local computing network

Star, Tire, Ring

Hub (switch) and switch (hub)

Optical fiber

Client

Grade

21-25 "5"

16-21 "4"

Net is a group of computers connected to each other by a communication channel. The channel provides data exchange within the network (that is, data exchange between computers in a given group). The network may consist of two or three computers, or it may unite several thousand PCs. Physically, data exchange between computers can be carried out via a special cable, telephone line, fiber optic cable or radio channel.

Computers on the network can be connected:

• directly with each other (so-called point-to-point compound);
• through intermediate communication nodes.

Computers connected to a network can perform two functions: they can be workstations or servers.

Work station- this is any working computer on the network that is not a server, as a rule, users work behind them. Requirements for workstations are determined by the range of tasks of the station. Typically, the main requirements are the requirements for speed and the amount of RAM.

Servers- these are computers that manage the entire network and accumulate all the data of workstations. Servers can work in automatic mode - they stand without a keyboard and sometimes even without a monitor, but in any case, the servers perform the functions of network management and data concentration. Network Administrator- a person whose responsibilities include all issues related to the installation and operation of the network, as well as solving all problems related to the rights and capabilities of network users.

Usually, the largest and most powerful computer online. However, development computer technology obviously leads to a reduction in internal components - the computer becomes faster and more economical. Therefore, in a short time, the server can become outdated faster than ordinary computers, which do not have such high requirements.

It is customary to distinguish between local and global networks. In essence, the main difference between them is already clear from the names, but there are also some significant technological differences.

Local networks(from English local - local) - these are networks consisting of closely spaced computers, most often located in the same room, in the same building or in closely spaced buildings. Local computer networks covering a certain enterprise or firm and uniting heterogeneous computing resources in a single environment are called corporate(from English corporate - corporate, general). Examples: banking network, educational institution network.

The most important characteristic of local networks is the data transfer rate, so computers are connected using high-speed adapters with a data transfer rate of at least 10 Mbps. Local networks use high-speed digital communication lines. In addition, local networks must be adaptable and flexible: users must be able to locate computers connected to the network where they need to, add or move computers or other devices, and disconnect them as needed without interrupting the network.

Combining computers into a single network provides network users with new opportunities that are incomparable with the capabilities of individual computers. The network is not an addition, but a multiplication of the capabilities of individual computers. A local network allows you to organize the transfer of files from one computer to another or others, share computing and hardware resources, combine distributed data processing on several computers with centralized storage of information, and much more. With the help of a computer local network, the collective use of technical resources is carried out, which has a beneficial effect on the psychology and behavior of the user not only on the network, but also in real life.

Topology of local networks

Topology is a network configuration, a way of connecting network elements (i.e. computers) to each other. There are three most common ways to connect computers to a local network: "star", "common bus" And "ring".

Star connection(Fig. 1). Each computer through a special network adapter connected by a separate cable to the merging device. If necessary, several networks with a star topology can be combined together, while the network configuration is branched out.

Advantages: With a star connection, it is easy to troubleshoot the network.

Disadvantages: The connection is not always reliable, since the failure of the central node can bring the network to a halt.

Common bus connection(Fig. 2). All computers on the network are connected to the same cable; this cable is shared by all workstations in turn. With this type of connection, all messages sent by each individual computer are received by all other computers on the network.

Advantages: in a "common bus" topology, the failure of individual computers does not bring the entire network to a halt.

software file operating driver

Flaws: it is somewhat more difficult to find a fault in the cable, and if the cable (single for the entire network) breaks, the operation of the entire network is disrupted.

Ring connection(Fig. 3). Data is transferred from one computer to another; at the same time, if one computer receives data intended for another computer, then it transfers them further (along the ring).

Advantages: load balancing, the possibility and convenience of cable laying.

Flaws: physical restrictions on the total length of the network.

The composition of the hardware and software depends on the scheme. The topology is chosen based on the needs of the enterprise. If the enterprise occupies a multi-storey building, then the scheme can be applied in it "snowflake"(Figure 4), which has file servers for different workgroups and one central server for the entire enterprise.

2016-02-10

Questions + on the topic of computer networks

Testing on the topic "Computer networks"

Option number 2.

Question 1. (Difficulty - A) The global network is.
Answer 1. A system of interconnected computers
Answer 2. A system of interconnected LANs
Answer 3. A system of interconnected local telecommunication networks
*Answer 4. system connected between local networks and computers of individual users
Question 2. (Difficulty - A) To connect two computers via telephone lines, you must have:
Answer 1. Modem * Answer 2. two modems
Answer 3. telephone, modem and special software
Answer 4. by modem on each computer and special software
Question 3. (Difficulty - A) E-mail is:
Answer 1. search program Answer 2. mail server name
Answer 3. mail program
*Answer 4. exchange of letters in computer networks (e-mail)
Question 4. (Difficulty - A) The HTTP protocol is used to:
*Answer 1. hypertext transfer Answer 2. file transfer
Answer 3: messaging control
Answer 4: run the program from a remote computer
Question 5. (Complexity - A) What components of a computer network are necessary for organizing a peer-to-peer local area network?
*Answer 1. modem, server computer
Answer 2: network card, network software
Answer 3. server computer, workstations,
Answer 4: communication lines, network card, network software
Question 6. (Difficulty - A) For viewing WEB-pages are intended:
Answer 1. search engines *Answer 2. browsers
Answer 3. Teleconferencing Answer 4. providers
Question 7. (Difficulty - A) Which of the following schemes for connecting computers is a closed chain?
Answer 1. Tire * Answer 2. Ring
Answer 3. Star Answer 4. No correct answer
Question 8. (Difficulty - A) Which cable provides data transfer rates up to 10 Mbps?
*Answer 1. Coaxial Answer 2. Twisted pair Answer 3. Optical fiber
Answer 4. there is no correct answer
Question 9. (Difficulty - A) A protocol is used to transfer files over a network.
Response 1. POP3 Response 2. HTTP Response 3. CMPT *Response 4. FTP

Question 10. (Difficulty - A) Choose the correct address Email:
Answer 1. ivanpetrov@mail
Answer 2. ivan_petrov.mail.ru
Answer 3. ivan petrov.mail.ru
*Answer 4. [email protected]
Question 11. (Difficulty - A) The data transfer rate is 6000Mbps. It makes up. Mbps
Answer 1.10
*Answer 2. 100
Answer 3. 3600
Answer 4. 36000
Question 12. (Difficulty - A) An e-mail address on the Internet is given: [email protected]. What is the name of the mail server?
Answer 1. [email protected]
Answer 2. fortune
*Answer 3. list.ru
Answer 4.list
Question 13. (Difficulty - A) A computer connected to the Internet must have
Answer 1. URL;
*Answer 2. IP address
Answer 3. WEB page;
Answer 4. domain name;
Question 14. (Difficulty - A) Choose the correct IP address of the computer on the network
*Answer 1. 108.214.198.112
Answer 2. 18.274.198.0
Answer 3. 1278.214.198
Answer 4. 10,0,0,1225
Question 15. (Complexity - A) The topology of a computer network in which all computers in the network are connected to a central node is called
Answer 1. Tire
Answer 2. Ring
*Answer 3. Star
Answer 4. There is no correct answer
Question 16. (Difficulty - A) Which top-level domain means "educational site"?
Answer 1. mil
Answer 2.gov
Answer 3.Com

*Answer 4. edu
Question 17. (Difficulty - A) Determine the 2nd level domain www.klyaksa.inform.net
Answer 1. klyaksa
Answer 2. inform
Answer 3. www
*Answer 4.net
Question 18
Answer 1. 215.128.255.106
Answer 2. 128.255.106
Answer 3.255.106
*Answer 4.106
Question 19. (Difficulty - A) Protocol is.
Answer 1. the ability of a computer to send files through information transfer channels
Answer 2. LAN device
*Answer 3. standard for data transmission over a computer network
Answer 4. standard for sending messages via e-mail
Question 20. (Difficulty - B) How long will it take to transfer a 128Kb file over a 128Kbps network?
*Answer 1. 8 s.
Answer 2. 1 p.
Answer 3. 1 min.
Answer 4. 10 s.

Test: LAN

Question #1 A: LAN is.

• Net for catching fish
• A computer network that connects a group of computers located in the same place
• Computer network that unites all computers Answer: 2;

Question #2: In order for the computer to connect to the network, you must have.

• Network cable
• Keyboard
• Network adapter
• network drive Answer: 1.3;

Question #3: There are networks.

Choose multiple answers:

• Local
• Global
• High
• deep
• Regional Answer: 1,2,5;

Question #4: If there are several computers, then an additional device is needed to connect them to the network.

Choose one of the answer options:

• Connector
• Switch
• Networker Answer: 2;

Question #5: The baud rate is characterized.

Choose one of the answer options:

• kb/cm
• kb/s Answer: 4;

Question #6: Specify the procedure for sharing your folder.

Specify the order of the answer options:

• Enable item open general access to this folder
• Right click on your folder
• select Properties
• select the access tab
• click Apply Answer: 2-3-4-1-5;

Question #7: What can't be done with LAN?

Choose one of the answer options:

• Communicate
• To play together
• Work on one document
• Pass candy Answer: 4;

Question #8: What is the name of the icon in windows with which we can access other computers on our local network?

Choose one of the answer options:

• network folder
• network
• Network icon Answer: 2;

| §4.1 Local and global computer networks

Lesson 24
§4.1 Local and global computer networks

Keywords:

Message
link
computer network
information transfer rate
the local network
global network

4.1.1. Transfer of information

Earlier, we have already said that information transfer is one of the most important information processes. Information is transmitted from the source to the receiver in the form of some sequence of signals, symbols, signs. For example, during a direct conversation between people, sound signals are transmitted - speech; when reading a text, a person perceives graphic symbols - letters. The transmitted sequence of signals, symbols, signs is called a message.

A communication channel (information transmission) is a system of technical means and a signal propagation medium for transmitting messages from a source to a receiver. When people communicate directly, information is transmitted using sound waves, when talking on the phone - using acoustic and electrical signals propagated through communication lines, when reading - using light waves.

Any transformation of information coming from a source into a form suitable for its transmission over a communication channel is called coding. Currently, digital communication is widely used, when the transmitted information is converted into a binary code.

Insufficient technical quality of communication channels and some other reasons can lead to distortion of the transmitted signal and loss of information. To avoid such situations, the code transmitted over the communication line is made redundant. Due to this, the loss of some part of the information during transmission can be compensated. In addition, in modern digital communication systems, all messages are divided into parts (packets, blocks). For each block, a checksum (the sum of binary digits) is calculated, which is transmitted along with this block. At the place of reception, the checksum of the received block is recalculated, and if it does not match the original amount, then the transmission of this block is repeated.

For centuries, mankind has used postal services to transmit letters; in the second half of the 19th century, sound transmission technology (telephone) was invented; Since the 1930s, telefax has been used to transmit images. Nowadays, for the transmission of texts, images, sound and many other types of information, computer networks- two or more computers connected by information transmission lines. With the advent of computer networks, it became possible to send a letter that arrives faster than a telegram, get an answer, find out the latest news, talk to a friend sitting at a computer hundreds of kilometers away, as if he were in the next room, book a plane ticket or a room in hotel, download desired program, ringtone or movie.

An important characteristic of a computer network is information transfer rate, or channel capacity. This value is defined as the amount of information in bits per second (bps) and in derived units: kilobits per second (1 Kbps = 1000 bps), megabits per second (1 Mbps = 1000 Kbps), gigabits per second (1 Gbps = 1000 Mbps).

Distinguish between local and global computer networks.

4.1.2. What is a local computer network

A local computer network unites computers installed in one room (for example, a school computer class) or in one building (for example, all computers located in a school building can be combined into a local network). A local area network allows users to share access to computer resources, as well as to peripherals(printers, scanners, disks, modems, etc.) connected to the network.

Local networks are peer-to-peer and dedicated server.

In small local networks, all computers are equal, that is, each of them can use the resources of the other. Users independently decide which resources of their computer (files, folders, disks) to make available to the entire network. Such networks are called peer-to-peer.

In networks with big amount users do not want all of them to have access to all computers on the network. When combining more than 10 computers, it is advisable to allocate the most powerful computer - the server (English server - serving). On the hard drive of the server, files (data and programs) are placed that are accessed by other network computers - clients. In addition, all network users can have access to peripheral equipment connected to the server (for example, a printer or scanner).

Each computer connected to the local network must have a special board - a network adapter. Its function is the transmission and reception of signals propagated through communication channels.

Connecting computers (their network cards) to a local network is carried out using various types of cables (twisted pair, optical fiber - Fig. 4.1) or via wireless channels (such as Wi-Fi).

Rice. 4.1. Cables:
twisted pair and fiber

A twisted pair is two insulated copper wires that are twisted together relative to each other. This twisting of the wires reduces the effect of interference on the signals transmitted over this cable. A twisted pair connection consists of several twisted pairs (2 or 4) covered with a plastic sheath. Data transfer rate - from 10 Mbps to 1000 Mbps.

Fiber optic cable transmits light through glass fibre. This type of connection provides a very high transmission speed, the length of the channel is hundreds and thousands of kilometers, and it is absolutely not subject to electromagnetic interference. Data transfer rate - from 100 Mbps to 10 Gbps.

The Wi-Fi wireless connection provides data transfer rates up to 300 Mbps.

4.1.3. What is a global computer network

Local networks, uniting dozens of computers in a small area, do not provide joint access to information to users located at a considerable distance from each other (for example, in different settlements).

global computer network is a system of interconnected computers located at an arbitrarily large distance from each other (for example, in different countries and on different continents).

Examples of global computer networks are regional and corporate networks. Regional computer networks provide an association of computers within the same region (city, region, region, country). Corporate computer networks are created to ensure the activities of various types of corporate structures that have territorially remote divisions (for example, banks with their branches).

The most famous and most extensive global computer network is the Internet. This network unites numerous local, regional and corporate networks, as well as computers of individual users, distributed throughout the world.

The basis of any global computer network are computer nodes and communication channels.

A node is a powerful computer that is permanently connected to the network. Subscribers are connected to computer network nodes - personal computers users or local networks.

A wide variety of physical channels are used for data transmission in global networks: electric cable; radio communication through repeaters and communication satellites; infrared rays (as in television remotes remote control); modern fiber optic cable; conventional telephone network.

An organization that provides users with a connection to the global network through their computers is called provider(English provider - supplier) of network services.

Task. The data transfer rate through some connection is 128,000 bps. How much time (in seconds) will it take to transfer a 625 KB file over this connection?

THE MOST IMPORTANT

Computer network- these are two or more computers connected by information transmission lines.

local computer network combines computers installed in the same room or building, and provides users with the ability to share access to computer resources, as well as to peripheral devices connected to the network. Local networks are peer-to-peer and with a dedicated server.

global computer network- this is a set of interconnected computers located at an arbitrarily large distance from each other (for example, in different countries and on different continents).

Questions and tasks

1. Familiarize yourself with the presentation materials for the paragraph contained in the electronic supplement to the textbook. What can you say about the forms of presentation of information in the presentation and in the textbook? What slides would you like to add to your presentation?

2. How do you understand the meaning of the phrase: “The possibility of transferring knowledge, information is the basis for the progress of the whole society as a whole and each person individually”? Discuss this question in a group.

3. Since ancient times, people have exchanged information in various ways, notified of danger or transmitted important and urgent information. Prepare a short report about one of the previously used ways of transmitting information.

4. What is a computer network?

5. What is a communication channel? How is the bandwidth of a communication channel determined?

6. How does a peer-to-peer LAN work?

7. How does a local network with a dedicated server work?

8. What type of local network is installed in your computer class? What functions does it perform?

9. What networks are called global? Give examples of such networks.

10. What communication channels are used for data transmission in global computer networks?

11. The data transfer rate over a certain communication channel is 512,000 bps. Transferring a file over this channel takes 16 seconds. Determine the size of the file in kilobytes.

12. Find out the names of network service providers in your area.

13. Build a graph of relationships connecting the concepts discussed in this paragraph.

Topic 1.3: Open Systems and the OSI Model

Topic 1.4: Basics of local networks

Topic 1.5: Basic LAN technologies

Topic 1.6: Basic software and hardware components of a LAN

Local networks

1.4. LAN Basics

1.4.1. Basic concepts of LAN

LAN classification

Computer network is a set of computers connected by data transmission channels. Depending on the distance between computers, the following computer networks are distinguished:

• local computer networks - LAN;
• territorial computer networks, which include regional MAN and global WAN networks;
• corporate networks.

A local area network is a LAN in which PCs and communication equipment are located on short distance from each other. LAN is usually designed to collect, store, transmit, process and provide distributed information to users within a department or company. In addition, the LAN, as a rule, has access to the Internet.

Local networks can be classified according to:

• management level;
• appointment;
• homogeneity;
• administrative relations between computers;
• topology;
• architecture.

Let's consider in more detail the classification of LAN

The following LANs are distinguished by the level of control:

• Workgroup LANs, which consist of multiple PCs running under the same operating system. In such a LAN, as a rule, there are several dedicated servers: a file server, a print server;
• LAN of structural subdivisions (departments). These LANs contain several dozen PCs and servers such as: file server, print server, database server;
• LAN of enterprises (firms). These LANs can contain over 100 computers and servers such as file server, print server, database server, mail server, and other servers.

According to the purpose of the network are divided into:

• computer networks intended for settlement work;
• information and computing networks, which are designed both for conducting settlement work and for providing information resources;
• information-advising, which, on the basis of data processing, generate information to support decision-making;
• information and control networks, which are designed to manage objects based on information processing.

The types of computers used are:

• homogeneous networks that contain the same type of computers and system software;
• heterogeneous networks that contain heterogeneous computers and system software.

According to the administrative relations between computers, we can distinguish:

• LAN with centralized management (with dedicated servers);
• LAN without centralized management (decentralized) or peer-to-peer (single-level) networks.

According to the topology (basic topologies), LANs are divided into:

• bus topology;
• star topology;
• ring topology.

By architecture (main types of architectures), LANs are divided into:

1. ethernet.
2. arcnet.
3. token ring.
4. FDDI.