1.3 Computer networks, connections and protocols

Question 1

LAN

Answer 1

Local Area Network. Small geographic area. All the hardware for the LAN is owned by the organisation using it. Wired with UTP cable, fibre optic cable or wireless using routers and Wi-Fi access points.

Question 2

WAN

Answer 2

Wide Area Network. Large geographical area. Infrastructure is hired from telecommunication companies who own and manage it. Connected with telephone lines, fibre optic cables or satellite links.

Question 3

Client-server network

Answer 3

A client makes requests to the server for data and connections. A server controls access and security to one shared file store. A server manages access to the internet, shared printers and email services. A server runs a backup of data.

Question 4

Peer-to-peer network

Answer 4

All computers are equal. Computers server their own files to each other. Each computer is responsible for its own security and backup. Computers usually have their own printers.

Question 5

Wireless access point

Answer 5

A networking hardware device that allows a Wi-Fi device to connect to a wired network.

Question 6

Router

Answer 6

A router sends data between networks. It is needed to connect a local area network to a wide area network. It uses the IP address on a device to route traffic to other routers.

Question 7

Switch

Answer 7

A switch sends data between computers on a local area network. It uses the NIC address on a device to route traffic.

Question 8

NIC

Answer 8

Network Interface Card/Controller. A computer hardware component that connects a computer to a computer network.

Question 9

Transmission media

Answer 9

The physical media over which data transmitted, e.g. twisted copper cable, fibre optic etc.

Question 10

The Internet

Answer 10

The Internet is a worldwide collection of interconnected computer networks. It is an example of a WAN, albeit the vary largest one which exists.

Question 11

DNS

Answer 11

Domain Name System. The Internet’s equivalent of a phone book. They maintain a directory of domain names and translate them to Internet Protocol (IP) addresses. This is necessary because, although domain names are easy for people to remember, computes or machines access websites based on IP addresses.

Question 12

Hosting

Answer 12

Websites stored on dedicated servers. Reasons include: Websites need to be available 24/7. Accessed by thousands of users at a time. Strong protection from hackers. They need an IP address that doesn’t change.

Question 13

The Cloud

Answer 13

Remote servers that store data that can be accessed over the internet. Advantages: Access anytime, anywhere and from any device. Automatic backup. Collaborate on files easily.

Question 14

Web server

Answer 14

A program that uses HTTP (Hypertext Transfer Protocol) to serve the files that form Web pages to users, in response to their requests, which are forwarded by their computers’ HTTP clients. Dedicated computers and appliances may be referred to as Web servers as well.

Question 15

Client

Answer 15

A client can be thought of as computing device which requests or is using the services from some remote/connected server.

Question 16

Network topology

Answer 16

The physical or logical arrangement of connected devices on a network. e.g. Computers, switches, routers, printers, servers etc.

Question 17

Star topology

Answer 17

Computers connected to a central switch. If one computer fails no others are affected. If the switch fails, all connections are affected.

Question 18

Mesh topology

Answer 18

Switches (LAN) or routers (WAN) connected so there is more than route to the destination. e.g. The Internet. More resilient to faults but more cable needed.

Question 19

Disadvantages of the cloud?

Answer 19

There is an ongoing monthly / yearly cost for hosting data and information. There are bandwidth problems and it all depends on speed of connection. The cloud relies completely on a stable internet connection. There is a lack of control because you are handing over data and information.

Question 20

What is a full mesh topology?

Answer 20

A full mesh topology is when every device is connected to every other device. One of the advantages is if you get a break in any of the connections, you now haven’t got a problem because the traffic can travel via an alternative route. A disadvantage of a full mesh network is that there is a lot more cabling and switch hardware required which will add the cost and will be impractical, especially in a large network.

Question 21

What is a partial mesh network?

Answer 21

Not every computer is connected to every other computer, but there are still multiple connections. We haven’t got a cable between every single computer, but we have got multiple paths to reach a destination. If you get a break in any of the connections, you still have other routes for the data to travel on. However there is a lot less hardware than a full mesh topology. Therefore lowers the cost and is more practical, which is good for large networks. There is still a lot more switch hardware required for a partial mesh topology than a star network topology.

Question 22

Which network topology best describes The Internet?

Answer 22

Partial Mesh Network.

Question 23

What are factors affecting the performance of a network?

Answer 23

Too many users - Too many users or devices on the same network can cause the network to slow down if there is insufficient bandwidth for each user.
Error rate - Less reliable connections increase the number of errors when data is transferred. This means the data has to be resent until it arrives correctly. The signal quality of wireless connections is dependant on the range of devices from the wireless access point and other environmental factors. The signal quality of copper cables is determined by the grade of material used which reduces interference. The length of the cable is also a factor.
Transmission media - Wired connections have a higher bandwidth than wireless connections. Fibre optical cables have a higher bandwidth than copper cables
Bandwidth - This is the amount of data that can be sent and received successfully in a given time. This is not a measure of how fast the data travels, but how much data can be sent on the transmission media. Bandwidth is measured in bits per second and is often called bit rate.
Latency - Latency is the delay from transmitting data to receiving it. Latency is caused by bottlenecks in the infrastructure of the network. For example, by not using switches appropriately segment traffic on a network. Hardware such as switches and transmission media, may not operate at the same speed.