Appointment of network equipment of computer networks of a workstation, server, modem, network. Workstation: what is it from the point of view of computer systems

Technical support of information and computer networks

Topic 10. Technical and software IVS

Control questions

1. What is Network Protocol?

2. What is OSI system? How many levels does it contain?

3. What are the names of the data blocks at each OSI layer?

4. Describe briefly the OSI physical layer.

5. Describe briefly the OSI data link layer.

6. Describe briefly the OSI network layer.

7. Describe briefly the OSI transport layer.

8. Describe briefly the OSI session layer.

9. Describe briefly the representative OSI layer.

10. Describe briefly the OSI application layer.

Structurally, the IVS contains:

· Computers (host computers, network computers, workstations, servers) located in network nodes;

· Equipment and data transmission channels, with associated peripheral devices;

· Interface cards and devices (network cards, modems);

· Routers and switching devices.

The networks can combine both single-user mini- and microcomputers (including personal ones) equipped with terminal devices for communicating with the user or performing the functions of switching and routing messages, as well as powerful multi-user computers (mini-computers, large computers). The latter perform efficient data processing and remotely provide network users with all kinds of information and computing resources. In local networks, these functions are implemented by servers and workstations.

Work station(workstation) - a computer connected to the network through which the user gains access to its resources. Often a workstation (as well as a network user, and even an application running on a network) is called a network client. Both ordinary and powerful computers and specialized computers can act as workstations. – "Network
computers ".

A network workstation based on an ordinary computer operates in both network and local modes. It is equipped with its own operating system and provides the user with everything necessary for solving applied problems. Workstations are sometimes specialized for graphics, engineering, publishing, and other jobs. In this case, they should be based on a powerful computer with two processors, a capacious and fast hard disk with SCSI interface, good 19 – 21-inch monitor (and sometimes dual monitors equipped with an appropriate graphics card – for example, one for displaying a project and one for displaying menus or emails).

Workstations based on networked computers can function, as a rule, only in network mode if there is an application server in the network. The difference network computer(NET PC) from the usual in that it is as simplified as possible: the classic NET PC does not contain disk memory (it is often called a diskless PC). It has a simplified motherboard, main memory, and from external devices there are only a display, keyboard, mouse and a network card, which provides the ability to remotely boot the operating system from a network server (this is a classic "thin client" of the network). To work, for example, on an intranet network, such a computer must have as many computing resources as a web browser requires.

Server(server) - it is a multi-user computer dedicated to processing requests from all workstations on the network, which provides these stations with access to shared system resources (computing power, databases, program libraries, printers, faxes, etc.) and allocates these resources. The server has its own network operating system, under the control of which all parts of the network work together.
The most important requirements for a server are high performance and reliability.

The server, in addition to providing network resources to workstations, can itself carry out meaningful information processing at the request of clients. Such a server is often referred to as an application server. Apps server - it is a powerful computer running on a network that has software (applications) that clients on the network can run on. There are two options for using an application server. At the request of the client, an application can be downloaded over the network to a workstation and executed there (this technology is sometimes called a "thick client"); on a workstation, upon request, it is allowed to load not only an application program, but also the required operating system (remote computer boot), but this requires the presence of a network card with a network ROM on the user's computer. At the user's request, the application can be executed directly on the server in another version, and then only the results of the work are transmitted to the workstation (the technology is sometimes called a "thin client" or "mode
terminal ").

The servers on the network are often specialized.

Specialized servers are used to eliminate the most "bottlenecks" in the network: the creation and management of databases and data archives, support for multicast fax and e-mail, management of multi-user terminals (printers, plotters), etc.

Examples of specialized servers.

1. File Server(File Server) is designed to work with databases, has large disk storage devices, often on fault-tolerant disk arrays of RAID up to a terabyte.

2. Backup server(Storage Express System) is used for backing up information in large multi-server networks, uses magnetic tape drives (streamers) with removable cartridges with a capacity of up to 5 GB; usually performs daily automatic archiving with compression of information from servers and workstations according to the scenario set by the network administrator (of course, with the compilation of the archive directory).

3. Fax Server(Fax server) – dedicated workstation for organizing effective multicast fax communication, with several fax-modem cards, with special protection of information from unauthorized access during transmission, with an electronic fax storage system (one of the options – Net SatisFAXion Software combined with SatisFAXion fax modem).

4. Mail server(Mail Server) – the same as a fax server, but for organizing electronic correspondence, with electronic mailboxes.

5. Print server(Print Server) is for efficient use of system printers.

6. Gateway servers on the Internet, they act as a router, almost always combined with the functions of a mail server and a network firewall to ensure network security.

7. Proxy server(Proxy Server) – effective and popular means of connecting local corporate networks to the Internet. Proxy server – a computer constantly connected to the Internet, loading information from the Internet into the database and transmitting it further over the local network. Communication of the corporate network with the Internet occurs through a proxy server, therefore, the protection of corporate information is effectively organized, all connections to the global network are monitored, communication with certain Internet sites is prohibited, the use of a number of protocols and the receipt of certain types of files is prohibited, as well as data filtering performed using the server's firewalls.

Computers with direct access to the global network are often referred to as host computers.

Today, in our everyday life, such a concept as a "workstation" appears more and more often. What is it? Many people guess about the answer, but not everyone can give a clear term. Let's consider some aspects associated with it, based on the principles inherent in computer technology.

Workstation: what is it in the broadest sense?

The definition of this term can be started with somewhat distant concepts, because it is found not only in the computer world. For example, the same synthesizers with built-in sequencers and sound processing facilities are also called workstations. Take at least the same KORG Trinity.

But if you define this term in a general sense, a workstation is, if you like, personal as it was called back in the days of the USSR. From the point of view of IT technologies, this term means a software and hardware complex designed to solve some specific problems. Roughly speaking, this is with an installed operating system, a set of programs and, if required, with connected peripheral devices (scanner, printer, etc.). However, in any case, only computer terminals connected to a local network are called a workstation.

Types of workstations

Considering that a computer is a workstation, its characteristics are very different from a terminal, called a server.

The workstations themselves, which are also called clients or client machines, are capable of functioning both in a network and in a local mode. If the local computer's own funds are sufficient for solving problems, the user uses them, working exclusively on his own machine. If you need the same Internet connection, data exchange or something like that, the client terminal addresses directly to the server.

As mentioned above, all software components can be installed on the local terminal, however, you can often find network workstations, called diskless (they simply do not have a hard drive). The network operating system is loaded on each computer from a central server, and all user information is stored on it. Sometimes the operating system can boot from an optical disc (if there is a floppy drive) or from a USB stick. In some cases, the same devices with a certain type of software can be used as a server.

The configuration of such computers is minimal: a simplified motherboard, monitor and keyboard, not counting peripherals. By the way, these types of stations are mostly used in banking institutions, since in this case the highest level of protection and security is provided.

The user of such a terminal simply cannot change the system settings or install additional software (the rights are limited by the administrator). And the information is also safe, because it is not physically present on the local computer. Thus, a networked diskless workstation is a kind of only a means of viewing and editing public data, in which it is absolutely impossible to change anything.

Executable tasks

As for the configuration, it can also be completely different. The functions of a workstation in providing, for example, a complete production or development process also depend on the initially assigned tasks, although in the general case it provides the specialist working with it with access to a certain set of tools to complete the task.

For example, for the development of application programs, as a rule, a programmer needs two monitors, for engineering or design work, powerful processor systems with a sufficiently large amount of RAM are needed, for graphics and animation, an even increased dedicated memory of the graphics accelerator will be required. In general, the range of tasks performed is quite wide.

Difference between workstations and servers

Now comes the most important thing. An ordinary workstation serves only to provide a workflow and interaction between itself, its operator and access to local or other resources by forming a request (call) to the server to which it connects.

The server is either a hardware-software complex, or simply software (in the case of its virtual version), which receives, processes and issues responses to requests from local client machines directly connected with it.

Server and workstation software

There are many differences in the software package. In the simplest case, you can look at the operating system. A network OS is mandatory installed on the server, but when a virtual server is created based on one computer terminal, this may not be required.

On workstations there is a minimum set of programs necessary to perform a certain range of tasks, but on the server there can be much more of them. In particular, this may be related to administration and such tools are simply not needed on client machines. In addition, local computers may not have an operating system, as is the case with diskless terminals, but an OS that is different from that of the server or any other computer on the network may be installed.

For example, Windows Server 2012 acts as a server room, while the client machines use Windows 7, 10, XP in different variations, or even Mac OS X and Linux. This does not mean that there will be no communication between local computers. It is carried out through the use of universal network protocols. So it is not so important what kind of OS is installed on each specific computer (and whether there is one at all).

Outcome

As a result, it can be noted that workstations are designed to perform specific tasks by a local user or specialist, and servers are designed to administer and monitor the network, manage connections and network resources at a priority level, provide access to the Internet or to shared resources within the network, and sometimes - to collect and store all information coming from local machines.

... The number of computers in the network has exceeded a dozen and it turns out that one cannot do without a server. Have to spend money on new hardware? Not always. On a home network, the only difference between a server and a workstation is the size of the hard drives. So that there was a place to store terabytes of music, photos and videos dear to my heart. And if you plan to distribute the Internet, centrally use databases, conduct video surveillance? Where the entire enterprise depends on servers, the level of requirements is an order of magnitude higher.

Note: this article will focus on a hardware server, that is, on a dedicated computer. There is also a software server - it can be brought up on any machine and run in the background.

The defining attribute of the server

Hardware, software, appearance and price - none of these parameters are decisive. The software on the server and workstation may be similar. The appearance of the system unit and the characteristics of the components do not always unambiguously indicate that this computer is just a server. The price level fluctuates in the widest range: somewhere it is appropriate to assemble a low-budget server, and buy a specialized workstation at the price of an SUV.

The main difference between a server and a workstation is in its interaction with a person. Namely: the server is shared and performs network tasks without operator participation; workstation (in everyday life referred to as a PC, and in technical documentation - AWP, automated workstation) each user has its own.

Equipment

Reliability and again reliability is the main criterion for server hardware. When assembling, they try to ensure maximum fault tolerance. The machine will have to work in a 24 x 7 mode, sometimes far from optimal conditions (especially for industrial systems).

Hot swapping is designed to reduce downtime. Hard drives, memory sticks and even a processor are subject to it (on those motherboards where there are two or more sockets for the CPU). The server power supply unit consists of two independent modules: one is out of order - the other is automatically connected.

The mouse, keyboard and monitor are used only during the initial server setup, and even then not always. Minimal graphics are enough to display service information, the same applies to sound. But on the other hand, the server is equipped with a remote control interface and, as a rule, more than one.

Some of the above may be inherent in a workstation, but rather as an exception. For a personal computer, user experience is just as important as performance in a given area. The design (both general and individual nodes, for example, a video card) and low noise, which are almost irrelevant for servers, are also taken into account.

Form Factor: External Difference Between Server and Workstation

If you wish, you can assemble a home server in absolutely any case, and even without it at all. However, for serious networking equipment, a 19-inch rack mount is provided. This form factor is called rackmount. The system unit is placed horizontally, its height is measured in units (the racks have strips with square mounting holes; three of these holes are equal to 1U).

Left - servers in a rack; on the right - an open server case

The lack of space in the racks led to the fact that the cases began to be made more and more narrow. A modern server takes one, rarely two units; an even more compact standard blade (from the English blade - a blade) is mounted in a special basket, and then in a rack. In all cases, quick access is provided for maintenance and possible replacement of components.

Industrial server solutions have a robust case with several stages of dust filtration, moisture protection and shock absorption. Servers for offices are also available in floor-standing or barebone form factors, but they are much less popular than the rack-mounted version.

A workstation is not only equipment, but also an element of the interior, therefore, enough attention is paid to design. There is plenty to choose from - stationary towers, compact monoblocks and stylish barebones. Those who are not satisfied with the standard appearance of the iron assistant can start modding.

The workstation may look different: like this ...
... or even so

Mobile PCs are extremely popular, despite the fact that a laptop is difficult to compete in performance with a desktop. But the server does not need portability: once installed in a permanent place, it will spend its entire service life there.

Operating system

A common feature of user operating systems is an intuitive, eye-pleasing graphical interface. The ubiquitous Microsoft Windows and MacOS, which reign supreme in the world of professional graphics and sound, can boast of an attractive "appearance".

An ordinary user has hardly heard of FreeBSD or OpenBSD, and from a huge number of Linuxes, he is familiar only with Ubuntu. Not surprisingly - created decades ago for servers, unix-like systems to this day manage both individual nodes and large data centers. They carry out their service modestly, without being conspicuous (in the literal sense, because they do not have a graphical shell).

Note: This is not to say that Windows systems are exclusively user-specific. Windows Server 2003 is an example.

For server operating systems, the rule applies: minimum external effects, maximum functionality. Of course, modern "nyx" can be transformed - many beautiful and stylish skins have been created by enthusiasts; however, sysadmins prefer to use the command line. The lack of visual effects is compensated by the speed. In addition, server-OSs are very compact - for security reasons, they are often placed on a secure flash card, from where they are loaded.

Putting knowledge into practice

"Why do we need another computer, because there are enough of them already?" - often hears an IT specialist from a frugal manager. A novice system administrator should spend some time preparing arguments in order to convincingly and intelligibly explain to his superiors what is the difference between a server and a workstation, and the application for the necessary equipment will be approved.

Server (Server)	Work station (Workstation)
Interaction with the user and other computers on the network
Operates without operator participation. Performs network-wide tasks, responds to requests from local machines and other servers	Executes user commands. Sends client requests to the server
Hardware features
Reliability, the minimum number of possible points of failure. Hot replacement of failed components. Control and monitoring devices are connected only at the start-up stage. Lack of unnecessary powerful graphics and audio controllers. Remote control interface (one or more)	Everything is organized in such a way as to ensure a comfortable environment for the user and, at the same time, maximum productivity. Display characteristics play a significant role - color quality, viewing angle, etc .; the ergonomics and appearance of the mouse and keyboard, as well as peripheral devices (MFP, graphics tablet, etc.)
Form factor
Mounts on a standard 19 ”rack or cabinet chassis. The body is made as compact as possible. If necessary, there is dust-moisture protection and shock absorption. The hardware part is easily accessible for maintenance and replacement	Along with the desktop, compact (monoblock, barebone) and mobile versions of workstations are popular. In all cases, design is given credit

Workstation composition.

Automated workstation (AWS) of the end user by the information system

Appointment and composition of AWP. Characteristics of the types of support for AWP

AWP Is a set of information resources and software and hardware that provide the user with data processing and automation of management functions in a specific subject area.

AWP has a problem-professional orientation and allows the user to transfer to a computer the execution of typical repetitive operations related to the accumulation, systematization, storage, retrieval, processing, protection and transmission of data.

The composition of the AWP is determined:

Features of professional orientation of a specialist;

The level of management tasks (tactical, strategic, predictive);

The peculiarities of the tasks to be solved (for specialists: the regulation of documents - repeatability in terms, a variety of regulatory and reference and operational information, etc.; for managers: setting strategic goals, planning, choosing sources of funding, policy formation, etc.).

18. Classification of computers.

19. PC structure.

A PC includes three main devices: a system unit, a keyboard, and a monitor. However, to expand the functionality of a PC, various additional peripheral devices can be connected to it: printing devices (printers), various manipulators (mouse, joystick, trackball, light pen), information input devices (scanners, graphic tablets - digitizers), plotters, etc.

These devices are connected to the system unit using cables through special slots (connectors), which are usually located on the back of the system unit. Additional devices will interfere with the presence of free slots on the motherboard directly to the system unit, for example, a modem for exchanging information with other PCs via the telephone network. As a rule, PCs have a modular structure (the structure of a modern PC is shown in Figure 3.1). All modules are connected by a common bus (system bus).

20. Workstation and server.

In any case, a workstation is the end point of interaction of a specialist with the necessary tools based on computer technology. Workstations are designed to perform end tasks and interact with the operator.

Server- a remote computer whose task is to issue requests to end clients connected to it (be it workstations, access terminals, other servers).

A server can be understood as a special program that responds to requests from other client programs on a local or global network. In this case, one of the workstations can act as a server, the purpose of which is to service requests from other network clients.

Or a server is understood as a special hardware and software complex consisting of several powerful computers of a special configuration, which is designed exclusively for processing requests. That is, it is not only a specially configured program on one of the workstations in the network, but a special productive computer or their whole network, which are busy only with responding to requests. For such platforms, special hardware configurations are developed, which are easily interfaced with each other, forming a super-computer (cluster).

Typical servers are intended for:

• processing and forwarding mail on the network,
• processing queries to databases,
• providing access to web resources,
• redirecting or distributing traffic on the network (proxy servers),
• storing and transferring files on the network,
• ensuring the interaction of game clients.

Other configurations are possible.

How does a server differ from a computer (workstation)?

The main property of the server is the issuance of automatic responses to requests from connected clients. And the workstation is designed to work with the end user only.

Our company offers turnkey solutions for workstations, server hardware and software for both workstations and servers.

21. Classification of computer networks.

After humanity created personal computers, it took a new approach to the organization of systems that process data, as well as the creation of new technologies in the field of storage, transmission and use of information. Somewhat later, the need arose to move from the use of separate computers operating in systems that process data centrally to systems capable of processing data in a distributed manner. Distributed data processing is the kind of information processing that is performed by independent, but interconnected computers, which are a distributed system. A computer network is a set of computers that are interconnected by communication channels, which allows you to create a single system that fully meets the requirements of the rules of distributed information processing. Thus, the main purpose of computer networks is joint data processing, in which all components of the system participate, regardless of their physical location. The classification of computer networks involves their division into types of computer networks, depending on the territorial location of computers and other components relative to each other. Thus, the classification of computer networks presupposes their division into: Global - these are computer networks that unite subscribers, which are located at a great distance from each other - from hundreds to tens of thousands of kilometers. Such networks make it possible to solve the problem of combining information resources of all mankind, as well as to organize instant access to these resources; Regional networks are computer networks that connect subscribers, which are located at less than in global networks, but still significant distances. An example of a regional network is the network of a large city or a separate state. Local networks are computer networks that unite subscribers that are located at relatively short distances from each other - most often in the same building or several nearby buildings. These are networks of enterprises, offices of companies, firms, etc. In addition, the classification of computer networks assumes that global, regional and local networks can be combined, which makes it possible to create multi-network hierarchies, which are powerful tools that allow you to process huge information arrays and provide almost unlimited access to information resources. Among other things, the classification of computer networks, or rather its understanding, makes it possible to build just such a system that will fully satisfy the needs of an enterprise, office, city or state in information. In general, computer networks consist of three subsystems nested within each other: a network of workstations, a network of servers, and a basic data transmission network. A workstation (can be represented by a client machine, workstation, subscriber station, terminal) is a computer at which a subscriber of a computer network works. A network of workstations is a set of workstations, as well as communication means, which are designed to ensure the interaction of workstations between themselves and the server. A server is a computer that performs general network tasks and provides various services to workstations. A server network is a collection of network servers, as well as communication facilities designed to connect the servers to the core network. A core data transmission network is a collection of means for transmitting information between servers. The core network includes communication channels and communication nodes. A communication center is a set of switching means, as well as information transmission, concentrated in one point. The purpose of a communication center is to receive data that comes through communication channels, as well as transmit them to channels that lead to subscribers.

22. Types of data transmission channels.

The data transmission channels used in computer networks are classified according to a number of characteristics. First, according to the form of information representation in the form of electrical signals, channels are divided into digital and analog. Secondly, according to the physical nature of the data transmission medium, communication channels are distinguished: wired (usually copper), optical (usually fiber-optic), wireless (infrared and radio channels). Third, according to the method of dividing the medium between messages, the above-mentioned channels with time (tdm) and frequency (fdm) division are allocated. One of the main characteristics of a channel is its bandwidth (information transmission rate, i.e. information rate), which is determined by the channel bandwidth and the method of encoding data in the form of electrical signals. Information rate is measured by the number of Bits of information transmitted per unit of time. Along with the informational one, the bean (modulation) rate is operated, which is measured in baud, that is, the number of changes in the discrete signal per unit of time. It is the Baud rate that is determined by the line bandwidth. If one change in the value of a discrete signal corresponds to several bits, then the information rate exceeds the bad one. Indeed, if n bits are transmitted on the baud interval (between adjacent signal changes), then the number of signal gradations is equal to 2n. For example, when the number of gradations is 16 and the speed is 1200 baud

One baud corresponds to 4 bps and the information rate is 4800 bps. With an increase in the length of the communication line, the signal attenuation increases and, consequently, the bandwidth and information rate decrease.

23. Digital and analogue channels.

Under communication channel understand the totality of the propagation medium and technical means of transmission between two channel interfaces or C1-type joints (see Fig. 1 1). For this reason, the C1 joint is often referred to as a channel joint.

Depending on the type of transmitted signals, two large classes of communication channels are distinguished, digital and analog.

Rice. 25. Digital and analogue transmission channels

A digital channel is a bit path with a digital (pulse) signal at the input and output of the channel. A continuous signal arrives at the input of an analog channel, and a continuous signal is also taken from its output (Fig. 25).

Signal parameters can be continuous or take only discrete values. Signals can contain information either at each moment of time (continuous in time, analog signals), or only at certain, discrete moments in time (digital, discrete, pulse signals).

Digital channels are PCM, ISDN, T1 / E1 and many others. Newly created SPDs are trying to build on the basis of digital channels, which have a number of advantages over analog ones.

Analog channels are the most common because of their long history and ease of implementation. A typical example of an analog channel is a voice frequency channel (ctch), as well as group paths for 12, 60 or more voice frequency channels. The PSTN telephone circuit typically includes numerous switches, splitters, group modulators, and demodulators. For the PSTN, this channel (its physical route and a number of parameters) will change with each next call.

When transmitting data, there must be a device at the input of an analog channel that would convert the digital data coming from the DTE into analog signals sent to the channel. The receiver must contain a device that converts the back-received continuous signals into digital data. These devices are modems. Similarly, when transmitting over digital channels, the data from the DTE has to be converted to the form adopted for this particular channel. This conversion is handled by digital modems, very often called ISDN adapters, E1 / T1 line adapters, line drivers, and so on (depending on the specific type of channel or transmission medium).

The term modem is used widely. This does not necessarily imply any modulation, but simply indicates certain conversion operations of signals coming from the DTE for their further transmission over the channel used. Thus, broadly speaking, modem and data link equipment (DCE) are synonymous.

What is a Server? At its core, it is a powerful computer that can smoothly perform various tasks and process information that comes in a large stream. Server machines are often installed in large companies. In terms of their functionality and purpose, servers are completely different.

What is a server for?

Any company, especially a large one, cannot do without its own server. The larger the company and the larger the number of users, the more powerful it will be required. Why do you need a server? It stores common information resources and, thanks to its work, several computers can have shared access to them at the same time, phones, faxes, printers and other devices that have access to a common network can also be connected to it.

What is the difference between a server and a regular computer?

The difference between the two comes from what tasks they perform. A computer is understood as the standard characteristics that any PC has at home or at work. What is a server - a computer that performs only certain tasks, it must process requests from other devices, as well as:

1. Serve the devices connected to it.
2. Have better performance.
3. Special accessories must be installed on it.
4. It should ignore the graphics capabilities of the systems.

The difference between a server and a workstation is that the workstation is designed only to ensure a high-quality work process. She does not interact with anyone, except for the operator and the server. The server communicates with all the machines that are connected to it over the network. He knows how to receive requests, process them and issue responses.

How is hosting different from a server?

It is not difficult to understand this issue. There are many different sites on the Internet. Data from sites must be placed on a server, roughly speaking, on which has an Internet connection. Having installed a website on it, it is serviced from the server. To optimize the work of a server, which cannot exist without software, you need hosting, its services can be purchased on the Internet.

Hosting and Server - What's the Difference? You can host your own website on the hosting. As a hosting owner, you can have your own server or rent it from a company. This is especially convenient for those who have not yet dealt with the operation of the server and do not want to spend their time studying the settings, trying something new by trial and error, closely monitoring the server's work and dealing with its software.

What do you need to create a server?

This is an expensive pleasure that a large company can easily afford, but for the average user it promises large financial costs. What do you need to make a server?

• have an idea of ​​what a server is;
• very good computer;
• own Internet channel, the speed must be high;
• stable operating system;
• assembly. It comes in two types of platforms, Java and C ++;
• patience and desire.

What does the server consist of?

Compared to the bundle of a conventional computer, it has several significant differences. The server machine consists of a central processor and a motherboard, only several processors on the board can be installed, and many more slots that serve for connection. What else is included in the server is the kernel, which is an important constituent element of its work.

What is Server Core? It manages all work processes and collects them into one whole. One of its main tasks is to interact with a variety of applications that are launched in the normal user mode. In general, server computers are powerful machines, but they consume a lot of electricity; to save it, some of the functions of a regular computer are missing.

What you need to know about servers

Understanding the work and purposes of such machines, we can distinguish types of servers that differ in their type. Among the total number, the main ones stand out:

1. The mail server is designed to send and receive mail messages.
2. A file server is required in order to store access to certain files.
3. What is a media server is clear from the name. It serves to receive, process and send audio, video or radio information.
4. What is the database server for? It is used to store and work with information that is formed in the form of a database.
5. What is the terminal server used for? It gives users access to certain programs.

What does an internal server error mean?

Each of the users at least once faced a problem when, when loading the site, the message "500 internal server error" appears, which notifies that an internal server error has occurred. The number 500 is the HTTP protocol code. What does server error mean? It is assumed that the software side of the server, although technically working, contains internal errors. As a result, the request was not processed in operational mode, and the system issued an error code. A server error can occur for a variety of reasons.

There is no connection to the server, what should I do?

Errors and malfunctions in the complex operation of the system occur almost every day. Users often face the problem that the server is not responding. In this case, it is necessary:

1. Make sure that the problem only occurs with a specific server. It may be that these are problems in the user's computer, his Internet connection or settings. Restart your computer
2. You need to double-check the requested web page title or IP address. They could change or cease to exist.
3. The reason for the lack of communication may be a security policy. The computer's IP address can be blacklisted by the server.
4. The prohibition can be on the user's computer itself. It may be that the address is being blocked by an antivirus program or the corporate network at work.
5. The connection error may be due to the fact that the request to connect to the server simply does not reach the addressee due to problems in intermediate nodes.

What is DDoS Server Attack?

A number of actions carried out on the Internet by hackers that lead to the fact that ordinary users cannot access certain resources are called DDoS attacks (Distributed Denial Of Service). What is a DDoS server is when a large number of requests arrive simultaneously from all over the world to the north, which is susceptible to attack. Due to the huge number of false requests, the server completely stops its work, it happens that it is impossible to restore it.