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Classified in Computers

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1º.- What Is a computer network? A computers network is a set of computers connected to Each other so they can share resources and exchange information

2º.- Types Of networks according to its size. Definition and classification.

Local area networks or LANs: They interconnect lots of different computer devices, such as personal Computers (PCs), workstations, printers and other equipment. These devices are Usually in the same buildingor in Buildings that are close together. They are private networks that allow users To share devices and programs, or send files and emails. One example of a LAN Is an Ethernet.

- A metropolitan area Networkor MAN: It is a computer network Larger than a local area network, covering an area of a few city blocks to the Area of an entire city, possibly also including the surrounding areas. A MAN is Optimized for a larger geographical area than a LAN, ranging from several Blocks of buildings to entire cities. A MAN might be owned and operated by a Single organization, but it usually will be used by many individuals and Organizations. MANs might also be owned and operated as public utilities.

- Wide area networks or WANs: They cover a large geographical area such as a country or continent. Users are Usually connected together via the telephone network or devices such as Switches or routers. The primary function of these devices is to guarantee that Packets of data reach their destination. To do this, they have tables of data Telling them the correct routes. The best example of WAN is the Internet.

3º.- Types Of networks according to its property. Definition and classification.

Public networks:A public network is a type of network where Anyone, namely the general public, has access. This is in contrast to a private Network, where restrictions and access rules are established in order to Relegate access to a few. Since a public network has few or no restrictions, Users need to be wary of possible security risks when accessing it. The Clearest example is the Internet.

- Private networks:a private network is a network that uses Private IP address space. These addresses are commonly used for home, office, And enterprise local area networks (LANs). The most common use of private Addresses is in residential networks, since most Internet service providers (ISPs) only allocate a single publicly routable IP address to each residential Customer, but many homes have more than one computer or other Internet Connected device, such as smartphones. In this situation, a network address Translator (NAT) gateway is usually used to provide Internet connectivity to Multiple hosts.

Private addresses are also Commonly used in corporate networks, which for security reasons, are not Connected directly to the Internet.

- Virtual Private networks: A Virtual private network (VPN) extends a private network across a public Network, such as the Internet. It enables a computer to send and receive data Across shared or public networks as if it is directly connected to the private Network, while benefiting from the functionality, security and management Policies of the private network. A VPN is created by establishing a virtual Point-topoint connection through the use of dedicated connections, virtual Protocols, or traffic encryptions.

4º.- Types Of networks according to its functionality. Peer to peer networks and cliente server networks.

In home and small office networks, a decentralized Network is often used, where every user may make their local folders and Printers available to others. This approach is sometimes

denoted a Workgroup or Peer-to-peer network topology, since the same computer may be used as client as Well as server.

In large enterprise networks, A centralized file server or print server, is typically used. Servers operate Within a client-server architecture. Servers are computer programs running to Serve the requests of other computers, the clients. It facilitates the clients To share data, information or any hardware and software resources. The clients Typically connect to the server through the network. Typical computing servers Are database server, file server, mail server, print server, web server,gaming Server, and application server.

5º.- Topologies. Types and know to identify them: linear, Ring and Star

LINEAR: The machines are Connected to the same transmission medium called bus. It consists of a single cable (coaxial) which links sequentially all the machines of the net.This type of network is in disuse.

- RING: A ring network is a Local area network (LAN) in which the nodes (workstations or other devices) are Connected in a closed loop configuration. Adjacent pairs of nodes are directly Connected. Other pairs of nodes are indirectly connected, the data passing Through one or more intermediate nodes.

The connections can consist of Wired or wireless links.

- STAR:A star network is a local area network (LAN) In which all nodes (workstations or other devices) are directly connected to a Common central computer, switch, hub or concentrator. Every workstation is Indirectly connected to every other through the central computer. In some star Networks, the central computer can also operate as a workstation.

In a star network, a cable Failure will isolate the workstation that is linked to the central computer, But only that workstation will be isolated. All the other workstations will Continue working normally. If any workstation goes down, none of the other Workstations will be affected. But if the central computer goes down, the Entire network will suffer degraded performance or complete failure.

6º.- Classification of Ethernet: 100 Base-T and 1000 Base-T

Ethernet networks are wired And they are still very popular because they are very easy to understand and Install, and are very flexible. The two types of network used are Ethernet 100 Base-T or Ethernet 1000 Base-T: o The number indicates the transmission speed In Megabits per second: 100 Mbpsand 1000 Mbps, respectively. O The letter T indicates the type of cable used to Transmit data. The cable consists of twisted pairs of copper wire with RJ45 Connectors at each end. These cables are used to connect the network.

7º.- Types Of cable: Twisted Pair (UTP and STP): UTP (unshielded twisted pair) cable is made up of 8 copper wires twisted together In 4 pairs with an RJ45 connector at each end. STP (shieldedtwisted pair ) is a safer cable to transmit Data. The isolation around the cable is increased, but it is more expensive.

and Optic fiber An optical fiber cable is a Cable containing one or more optical fibers that are used to carry light. The Optical fiber elements are typically individually coated with plastic layers And contained in a protective tube suitable for the environment where the cable will be Deployed

8º.- Which Connector do the twisted pair use? RJ45 connector

9º.- Types Os Wireless networks. Definition. Wireless Networks or WLANs (wireless local area networks) are data communication systems That do not use wires. They can be used instead of wired LANs. These networks Use electromagnetic waves to transmit data and to connect several computers Together. The computers on WLANs must have a wireless adaptor and a network Card.

10º.- Elements of a LAN. Definition

Network Cards :is an electronic device that connects a computer in LANHubs. These are passive elements .They are old and slow ,as all the Communications packets are transmitted indiscriminately to all the ports. Switch:they are active elements.They Are faster than hubs,because the data is transmitted between the two nodes or Computers involved. Routers:it is a The device to join or connect multiple networks together.

11º.- What Is the MAC address in a network card? A Media access control address (MAC address) is a unique identifier assigned to Network interfaces for communications on the physical network segment. A Network node may have multiple networks cards and each network card must have a Unique MAC

address. MAC addresses are Formed by six groups of two hexadecimal digits, separated by hyphens (-) or Colons (:)

12º.- Which Is more modern and faster: HUB or SWITCH? Switches are faster and modern than hubs

13º.- What Is the protocol TCP/IP? What is it for? Computers communicate with each other using a communication code called The network protocol, a set of rules and conventions that help to ensure reliable Transfer of information. Network protocols must carry out five functions:

- Correctly locate any Computer on the network.

- Understand all the messages, Regardless of the type of communication used (ADSL, cable,… )

- Understand all the messages, Regardless of the operating system used by the connected computer (Windows, Linux, Mac OS)

- Allow secure information Exchange.

- Finish the correction Correctly.

14º.- What Is IP address? How is it formed? All Computers that are connected to the Internet must be identifiable so that they Can be located quickly and accurately. Each computer is therefore assigned its Own unique address called an IP address. Each IP address is made up of four Groups of numbers separated by full stops. Each of these groups can have a Value of between 0 and 255.

15º.- Classification of networks according to its IP address.

Class A was designed to meet The needs of large networks (Internet servers) . This class will only support 126 networks; but each network can support 16,777,214 hosts. The first octet of This class ranges from 1 to 126.

- Class B was designed for Medium-sized networks( big companies with computers all around the world). This Class will support 16,384 networks; and limited to 65,534 hosts per network. The first octet of this class ranges from 128 to 191.

-- Class C was designed for small networks (LAN and Intranets) ; thus the number of hosts per network will be small, However it will support many more networks total. Class C supports 2,097,152 Networks; but only 254 hosts per network.In this class, three octets are used to identify the network. The first Octet of this class ranges from 192 to 223

16º.- Differences between domain and workshops. In a workgroup:All computers are peers; no computer has Control over another computer.Each Computer has a set of user accounts. To log on to any computer in the Workgroup, you must have an account on that computer.There are typically no more than twenty Computers.A workgroup is not protected By a password.All computers must be on The same local network.

In a domain:One or more computers are servers. Network Administrators use servers to control the security and permissions for all Computers on the domain. This makes it easy to make changes because the changes Are automatically made to all computers. Domain users must provide a password Or other credentials each time they access the domain.If you have a user account on the domain, you Can log on to any computer on the domain without needing an account on that Computer.You probably can make only Limited changes to a computer's settings because network administrators often Want to ensure consistency among computers.There can be thousands of computers in a domain.

The computers can be on different local Networks.

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