Networks

Question 1

What does LAN stand for?

Answer 1

Local Area Network

Question 2

What does WAN stand for?

Answer 2

Wide Area Network

Question 3

Define LAN

Answer 3

Operates on a single site or within a single organisation across buildings close to each other. Uses its own Ethernet hardware and cabling to transmit data.

Question 4

Examples of LAN

Answer 4

Small company networks and home networks

Question 5

What is an ethernet cable?

Answer 5

Wired communication used to connect devices in a LAN

Question 6

Define WAN

Answer 6

Connects LANs together to form larger networks. Used to connect computers over a larger distance, often nationally or internationally. Uses third party or external hardware and cabling, including satellites, phone lines and the internet.

Question 7

Examples of WAN

Answer 7

Multi-national banking network and the internet

Question 8

Factors that affect network performance (total 8)

Answer 8

1. Number of active devices
2. Interference from other devices nearby

or !! bandwidth; type of cabling; performance of the server; signal strength; distance from the Wi-Fi access point; topology

Question 9

What is Bandwidth?

Answer 9

Bandwidth is the amount of data that can be transferred in a given time (eg 500Mbps), shared between the devices on a network.

Question 10

What drains bandwidth, and how to stop it?

Answer 10

Too many devices or heavy use (eg streaming video) may cause congestion and slow the network. You can limit the bandwidth available to individual users to address this.

Question 11

Wired ethernet cables - Coaxial copper cables vs fibre optic cables

Answer 11

Fibre optic cables transmit data as light, whilst coaxial cables transmit through electrical signals. Fibre optic cables are of higher bandwidth than copper cabling and can transmit more data simultaneously, over very large distances without interference or loss of signal quality. However, as high performance cables, they are expensive.

Question 12

What are the four main network hardware that are notable to connect devices?

Answer 12

Wireless Access Point (WAP)/ Wireless AP, Switch, Router, Network Interface controller/Card (NIC)

Question 13

What is the function of a Wireless Access Point (WAP)?

Answer 13

It creates a wireless network through radio waves which a Wi-Fi enabled device can connect to communicate with the network or the internet.

Question 14

What is the function of a switch?

Answer 14

It is used to connect devices on a LAN. Receives data packets and forwards them to the correct device using their unique individual Media Access Control (MAC) address.

Question 15

What is the function of a router?

Answer 15

Directs data packets from one router to another in different networks, sitting between LANs and WANs to join them together with a public IP address for the WAN and a private IP address for the LAN.

Question 16

What is the function of a Network Interface Controller/Card (NIC)?

Answer 16

It is a hardware component required to connect any device to a network. Wired and wireless versions are available. Nearly all computers have a NIC built directly into the motherboard.

Question 17

What are some types of topologies?

Answer 17

Star, mesh, bus

Question 18

How does number of active devices affect network performance?

Answer 18

• Increases no of data collisions (when data packets sent simultaneously collide)
• This could cause errors and retransmission

Question 19

How does interference from other devices nearby affect network performance?

Answer 19

• Eg bluetooth devices or microwave ovens
• Disrupts signal and the connection becomes unreliable
• Causes delays and unexpected disconnections

Question 20

Where are star topologies most often used?

Answer 20

Business and organisations where performance is essential. Also found in smaller offices and home networks owing to their simplicity.

Question 21

How does a Star network work?

Answer 21

Each device on the network is connected to a central switch which directs data packet transmissions to the correct device using their unique MAC (media access control) address. Some home routers will also have switches and WAP (Wireless Access Point)s capabilities.

Question 22

Advantages of a star network topology

Answer 22

Very reliable
- If one cable fails, the other nodes will be unaffected
Data collisions can be avoided by using this topology with a switch
- Network performance improved

Question 23

Disadvantages of star network topology

Answer 23

Cable required to connect every computer
- Expensive
- Requires switch to direct transmission to correct networked device
If switch fails
- All devices on the network will lose their network connection

Question 24

Full vs Partial mesh topology

Answer 24

In a full mesh topology, every node is connected to every other node, each sending its own signals and in addition, relaying data from other nodes. In a partial mesh topology, which is more common, some of the devices may be connected to one or two others. This is less costly and reduces redundancy.

Question 25

Advantages of mesh network topologiese

Answer 25

Highly robust - Network will automatically find a different route if there is a fault with one connection of node. Data can be transmitted from several devices simultaneously - Network can cope with high traffic Local networks can run faster than in a star network - Data does not have to travel via a central switch which

Question 26

Disadvantages of mesh topologies

Answer 26

Very expensive - Difficult to establish the connection Self-maintenance and network administration is complex - Difficult to expand the network.

Question 27

What is a network protocol?

Answer 27

A network protocol defines the rules that controls the way data is sent over the network.

Question 28

What are client-server model used for?

Answer 28

- Web servers - Application servers - Network Attached Storage (NAS) - Print Servers - Mail Servers

Question 29

What are the advantages of a client-server network? (6)

Answer 29

- Central storage of files so **users can access them from any computer**. - All client computers can search and update a central database to **avoid multiple copies becoming out of sync**. - **Backups** can be made centrally so that individuals do not need to back up their own client machines. - **Security** can be managed centrally using antivirus software on the server. - **Software** can be upgraded and installed centrally without having to visit each client machine. - **Client machine usage and behaviour can be monitored** to provide a history of use and to ensure correct procedures are followed.

Question 30

Disadvantages of client-server networks (3)

Answer 30

- Requires a **costly maintenance team** to manage the network and the server. - **Too many client requests** will **degrade server performance**. - If the **server or its network connection go down** then the server is lost for the whole network, thus preventing the whole network from functioning.