aziz728
Networks
Definition of networks:
Networks are a link between two or more different computers by means of tools and programs dedicated to networking that allow sharing between them, and information flows through the network in the form of electrical signals that are transmitted as small packets of information at very high speeds until they reach the target free of errors.
The types of networks are divided into several forms, some of which are divided according to the function, and some are divided according to the form.
Networking benefits:
Its benefits are innumerable, as it saves time, effort, money, and many solutions, for example:
1. Connecting different devices with each other, so that the transfer of files between devices becomes very smooth and very fast, and does not require any other media such as floppy disks, flash drives, or hard disks.
2. Linking one printer to a large number of devices, which saves a lot of money to buy multiple printers for each device.
3. It also helps to save large data in one place, and this helps in data security if the necessary precautions are taken by officials.
4. And now the Internet has become the largest model of networks, and you can realize the ease with which it provided data, learning, news, and so on.
There are two types of usage for grids:
The first type:
It is based on the client / server principle
In this type, the central computer that provides programs and data to others is called a server or server, and the computers connected to it are called clients.
And client / server networks require a network operating system such as Windows Server 2003 or Windows Server 2008 or others.
The second type:
It is based on the peer-to-peer principle
In it, all network computers are considered equal in terms of the function they perform in the network, that is, there is no specific computer assigned to it with central tasks such as a server, and devices in peer-to-peer networks communicate directly with each other, enabling them to exchange information, but they are less protected and costly than server networks. Client.
Local area networks, extended networks, wireless local area network, and the Internet:
Local networks (LAN), extended networks (WAN), wireless local area network (WLAN), and the Internet are types of networks according to connection characteristics, size, and distance, but the first two types are present in all networks, for example, you have 7 local devices. For the seven devices, the Internet.
In this example, the devices communicated with the provider in a server / client way, and it is a small local network because it is also connected to a global network .. called the Internet .. through its provider who provides the resources for it!
Therefore, the two types Lan and Wan are basic types of communication method between network devices.
A wireless local area network provides a wireless network connection covering short distances using radio waves or infrared waves without the need for traditional network cables.
There is also another division of networks according to the method of data transfer, including (star) and (annular), and this division is used with (Lan) networks.
How to connect between LAN and WAN
At home, we usually use a local area network and connect it to the Internet with our Internet Service Provider (ISP) via a modem, which is a small device that connects to your Internet Service Provider (ISP) to take advantage of all the Internet’s resources. The connection is via a regular cable, fiber optic cable, or home telephone line (ADSL) that runs from outside your home to the jacks on the back of your modem.
The ISP provides the wide area network (WAN) IP address, and all computers on your home network use LAN IP addresses.
All computers on the local area network (LAN) can communicate directly with each other, but they must pass through a central network gateway, and usually a modem is used with a router, which is the device that enables you to share your modem’s Internet connection with all your devices or that allow have access to your network.
Typically, the router and modem combine into one hybrid device and pass the internet connection to other devices in your home either via cable or wirelessly over a Wi-Fi network.
Here are some names and meanings of common acronyms related to our topic, which is networks:
Meaning of the word Internet:
The word Internet is derived from the International Network, which means the global network. According to the latest statistics, the Internet connects more than 10 million computers in more than 100 countries around the world. Most of these devices are owned by companies, universities, and government departments, in addition to individuals who own personal devices. They are permanently connected to the Internet, and the number of servers increases monthly, and so is the case for people who use the Internet.
World wide web:
Its abbreviation is WWW or W3 or simply Web. It is a huge collection of hypertext pages on the Internet Web traffic is growing faster than any other service on the Internet It makes it easier for people to find their way through the Internet It is not only the friendly face of the Internet it is more than that Web software It allows you to put links – Links – in your documents on the Internet, and these links are known as Hyper Text.
the network :
It is the connection of two or more devices together in order to exchange information, and the network can be local in nature, by connecting devices in a building, for example, and this is what can be called a local area network (LAN). Devices across flags is called a Wide Area Network (“WAN”) Computer networks use different methods of communication, starting with a regular telephone network, and ending with a special high-speed fiber-optic link.
Server:
It is a structure for connecting computer systems on the network, and the beneficiary system is usually a personal office device, or a workstation, while the server is a larger system that can store large amounts of data, and can implement the main applications – computer programs -, the Internet was built on the basis of the server structure / beneficiary; Then I passed it.
Client:
A computer that requests service from another computer. When a computer requests a subscription with an ISP service provider, it is considered a client of the ISP. .
System Administrator:
Often abbreviated to SA, this is the person responsible for computer administration in large companies. It may be several people or even a small section of the company. Duties performed by this administrator include installing, updating, and removing software, installing upgrades to operating systems, installing and configuring devices such as printers, modems, routers, gateways, and firewalls, and monitoring user-to-user performance. He is the person who sets up the network resources, registers users and their passwords, and maintains the resources.
Agent:
In a Client/Server system, that part of the system that performs the process of setting up and exchanging information on behalf of the Host or Server software.
Host host:
The central or controlling computer in a networked environment provides services that other computers can access over the network. The host is also a large system that can be accessed from the Internet. The term (host) is often used for the computer that allows users to access it.
Proxy Server:
A program that runs on a server located between your local logical network or the Internet and the Internet. In an attempt to hide the network structure from hackers. This program filters all outgoing connections so that they all appear as coming from the same machine. The proxy server also passes your request to the Internet, intercepts the answer, and passes it back to you at your network node. The system administrator can also regulate the external points to which users of the local logical network can connect. It is a method whereby a device – usually directed – responds to requests to enter certain sites, and thus it executes this request based on the orders it received and the guidance it was designed for.
Uniform Resource Locator (URL):
It is an abbreviation for Uniform Resource Locator It is the technical name for the address of the website on the Internet, or the place where a specific site is located, just as the house has a specific address to reach it for example, so there is a specific address to reach a specific site on the Internet such as accessing, for example, the “electronic countryside” on The Internet must know the URL, the URL of the electronic country is http://www.3asfh.net
Firewall or firewall:
A barrier in hardware, software, or both that allows traffic to flow in only one direction – out of a protected network… A firewall is a device commonly used to protect a network from unwanted intruders… It is the name given to a computer application that provides a connection to the Internet It monitors the information sent and received in your organization through the Internet, and can access your sensitive information. It is a security system to restrict access to computers on a local area network (LAN) from anywhere outside
Protocol:
In networks and communications, it is the official specification that defines the procedures to be followed when sending and receiving data. The protocols define the format, timing, sequence, and error checking used in the network.
Internet Protocol IP:
The Internet Protocol is the network layer of the TCP/IP protocol footer that tools on the Internet use to communicate with each other. The IP address (Internet Protocol address) is the address of each computer connected to a network, and each IP address has two ways of writing, either digital (TCP / IP Address) such as 212.26.66.3 or literal (FQDN), which are the addresses that we usually write in browsers such as ftp.reeef.com/ vb/new The real address is the digital one, but because it is difficult to memorize it, we write the literal address, but internally the literal address is translated into the corresponding digital address.
Transport Control Protocol (TCP):
Transfer Control Protocol (Transfer Control Protocol) This protocol passes information to the Internet Protocol (IP) and is responsible for ensuring that the message is received and understood.
Hypertext Transfer Protocol (HTTP):
Hyper Text Markup Language is an acronym for Hypertext Markup Language. A structural language used to describe web and Internet documents. Originally used only for defining structure, but now defining the structure, appearance, and location of elements, including fonts, graphics, text, hyperlinks, and many other details, it is a subset of SGML (Standard Generalized Markup Language). It is a means that makes it possible to browse through web documents, the user clicks on anchor points on a web document, which enables him to go to that document even if it is on another device.
File Transfer Protocol (FTP):
File Transfer Protocol, abbreviation for File Transfer Protocol… FTP supports a range of file transfer types and formats, including EBCDIC, ASCII, and binary format.
Point-to-Point Protocol (PPP):
Point-to-Point Protocol One of two means of exchanging masses of data over the Internet via telephone lines (the other method is SLIP)… PPP protocol provides a means of data compression and error correction and is still under development.
Post Office Protocol (POP):
Post Office Protocol allows the user to store his messages on the computer of the service provider company in order to retrieve them later. There are three versions of this system: POP, POP2, and POP3.
Serial Line Internet Protocol (SLIP):
Serial Line Internet Protocol is a protocol used to operate the Internet Protocol (IP) on serial lines such as telephone circuits. Usually when linking to a service provider that uses either PPP or SLIP.
Simple Mail Transfer Protocol (SMTP):
A protocol used to transfer email between devices.
Internet Block Pool (PING):
Packet Internet Grouper is used to test accessibility by sending an ICMP echo request to it and waiting for a response.
Domain:
It is that part of the DNS that determines your computer’s network location in the world.
Router:
A computer system that makes decisions about traffic directions on the Internet.
Domain Name System (DNS):
Domain Name System is a system for determining the IP addresses corresponding to named computers and domains.. The DNS consists of a series of information separated by dots … Domain Name Service is a program that converts Domain Names into IP addresses. Addresses.
Network Basic Input-Output System (NETBIOS):
Network Basic Input/Output System Allows machines running DOS to talk to and use network services. The same name is the name of a local area network protocol widely used in Microsoft products.
Bandwidth:
It is the amount of information that you can transmit on a specific line at a specific time… Bandwidth is measured in the number of pulses per second and is written (bps).
Bits per second:
BPS is the number of bits transmitted every second during a data transfer.
Kilobits per second:
KBPS is the number of bits transmitted per second during a data transfer process, measured in multiples of 1024 bits per second.
Kilobit:
A unit of measurement equivalent to 1024 bits, and is commonly used to specify the capacity of memory.
Kilobyte:
A unit of measure equivalent to 1024 bytes.
Megabyte:
A unit of measure equivalent to 1024 kilobytes or 1,048,576 bytes.
Dial-up:
Using the telephone or ISDN to connect the computer using a modem to the Internet service. It is the opposite of a permanent connection, which means that in order to get the service you have to make a phone call.
Unified Services Digital Network (ISDN):
An acronym for Integrated Services Digital Network, it is a new technology that contains voice and digital networks in one medium and is considered a high-speed communication service. It is an integrated services digital network. It is a standard for a worldwide digital communications network intended to replace all existing systems with a fully duplex synchronous digital transmission system. Computers and other devices connect to an ISDN network through simple, standard interfaces. When complete, ISDN systems will be able to transmit voice, video, and data in a single line—a task that currently requires three separate connections.
Internet Service Provider (ISP):
Internet Service Provider is the company that the user usually subscribes to in order to obtain an Internet connection, and this company is connected to the Internet directly from one of the CIX member companies.
Gopher Service:
A system developed by the University of Minnesota, USA, with the aim of facilitating the process of using the Internet. It relies on the search process through lists to read documents and transfer files.. Gopher can refer to files, Telnet sites, WAIS information centers, and others.
Remote connection (Telnet):
Telnet is an Internet protocol standard for remote connection services that allows a user to connect his machine to a host computer, making his machine a part of that remote computer.
Port Number:
The default input/output location for an Internet program. For example, FTP, Gopher, HTTP, and Talnet are all given unique port numbers so that the computer can know how to respond when connected to a specific port. Gopher servers usually talk over port 70, HTTP servers use port 80, and the SMTP email protocol always uses port 25. You can override these default values by specifying other values in the URL.
PORT (PORT):
Locating a specific program on a host computer on the Internet.. A few years ago, the user had to specify the port himself, port 23 for Telnet and port 21 for FTP, but today most programs specify the port automatically.
Winsock:
Windows confluence system, and if you want to access the Internet, you must have a file called winsock.dll located inside the system. The problem that is frequently repeated is that not all programs work with the same edition of Winsock. The trumpet application that many use is used to provide SLIP connectivity between their computers, and the Internet provides a copy of Winsock.
Upload:
The transfer of a file or other information from your computer to a server over a network link or modem.
Download:
In communications, the transfer of a file or other information from a server to your computer over a network connection or over a modem.
Applet:
A self-contained program designed to run in a specific environment, such as a Java program running in a browser.
User Account:
A security mechanism used to control access to a network that is established and maintained by the system administrator. Elements of a user’s account include a password, rights, and information about the groups the user belongs to.
Home Page:
The initial landing page on the Internet or a Web site. A start page may be associated with a single person, topic, company, non-profit organization, or school, and is a convenient place to jump from to other Internet pages or resources. Consider it the main section of the site.
Search Engine:
Some popular network types:
LANs
MANs Regional Networks
WANs
Internet
Networks have four popular types:
1. LANs
Local networks are restricted to one place, such as a building or adjacent buildings, and are characterized by cheapness and the availability of the necessary equipment for them. They are divided into 3 common communication techniques, which are:
•Ethernet
Token Ring
FDDI
2. MANs Regional Networks
Regional MAN networks are designed to transmit data across vast geographic areas, but they still fall under the name of local and are valid
To connect a city or two adjacent cities, and this type of network is used to connect optical fibers or digital means, this technology
Offers high speeds and MAN networks that can contain a number of LANs and are characterized by speed and effectiveness
One of its drawbacks is that it is expensive and difficult to maintain.
3. WANs
They are networks that cover very large areas such as connecting countries with each other. One of the advantages of this type is that it connects thousands of devices and transfers large amounts of data that cannot be transferred without it. Among its disadvantages is that it requires very expensive programs and devices and the difficulty of operating and maintaining it.
4. The Internet
Internet Network of Networks This network was designed mainly for purely military purposes during the days of the Cold War and then grew to be used for commercial purposes and so on.
Network Topologies:
Network Topologies is the form that allows network devices to communicate with each other and is called the physical form of the network or Network Topologies
Types of network design:
There are four main types of network topologies:
1. Linear Design Bus Topologies:
It is the linear carrier network and its structure is easier and simpler. It consists of a single cable on the network to which all devices are connected. Any device can send to any node, and this message is transmitted to all nodes on the network, but only the sender can read it, and the sender at this moment is him. In order to prevent conflicts that may result from trying to transmit to several devices simultaneously, the network uses a type of technology used in Ethernet networks, a technology known as CSMA/CD Carrier Sense Multiple Access and its simple definition is that if One of the devices wants to send a message, so he first senses the cable, and if he finds it busy, he waits until it ends… But what happens if he sends two devices at the same moment, both of them drop for a random period of time, then try again? Difficulty defines the problem on the network and the number of nodes on the network also affects the speed of performance.
2. Ring Design: Ring Topologies
It is a network that is circular in shape, at least in theory, where the signals travel from one node to another in one direction only, and each node communicates with two nodes directly, a node that sends it and a node that receives from it, and it actively participates in sending any message through the network, and in some cases it strengthens the signal Before passing it on to the next node, which in this case is the opposite of the linear carrier network, the ring network relies in order to avoid conflicts on a method called passing the tag, which is simply a tag that rotates in the network. No one can transmit at that moment until the transmission is completed. One of the advantages of this type is that it is also easy to install and cheap. One of its disadvantages is that when a problem occurs, it is difficult to determine, and if the cable is cut, the network stops completely.
3. Star Topologies
This type is considered one of the best types, and it is characterized by the presence of a central distributor (Hup) in which the cables of the devices are gathered. This distributor can be effective by strengthening the signals passing through it. A number of central collectors can also be connected in one network. One of the most important advantages of this type of network is that it It is easy to add or isolate nodes from it and easily identify the problem if it occurs and isolate any part of the network that does not affect the rest of the parts.
4. Multi-Directional Design: Mesh Topologies
In this type of network .. the design is more complex .. but it is more reliable because the device is connected in the network with many lanes .. so the backups are present.
Networks use a common language or a compatible protocol so that different devices can communicate with each other and understand each other.
Protocol Definition: A set of standards or standards used to exchange information between computers.
Components required to design a network:
In order for computers to form a network, they need a medium that transmits data, and in this case it is either a wire or a wireless medium. These computers also need an adapter, an Adapter, or a Network Interface Card to connect these devices to the computers that provide data or resources in the current networks. They are called Servers, while the computers that benefit from this data are called Clients.
The network needs network software installed on the devices connected to the network, whether they are servers or clients, and this program is either a network operating system
Network Operating System (NOS)
There must be an operating system that includes network management software such as Windows 2003 Server or Windows Server 2008 or others.
This program controls the network components and maintains the connection between the client and the server.
This was part of the definition of networks and their use and benefit from them, and we hope that we have succeeded in delivering the information to you, and God is the success.
