(GCSE ARCHIVE) Networks

Question 1

Network

Answer 1

Two or more nodes that are linked together in order to communicate, exchange files, or share recourses (such as printers).

Question 2

Local Area Network (LAN)

Answer 2

• Covers a small geographical area on a single site
• All hardware needed is owned by organisation using it
• Can be wired (e.g. with ethernet) or wireless.
• Used in businesses, schools, universities, homes

Question 3

Wide Area Network (WAN)

Answer 3

• WANs connect LANs in different geographical locations. (e.g. businesses with offices in different countries).
• Unlike LANs, hardware needed for WANs is not owned by organisations. It’s hired from telecommunication companies, because WANs are far more expensive than LANs to set up.
• WANs can be connected using telephone lines, satellite links, or radio links.
• The Internet is one big WAN.

Question 4

Personal Area Network (PAN)

Answer 4

• Connect devices over a very short range.
• Centred around a single user
• Use common wireless technology (e.g. Bluetooth).
• Bluetooth signals are strong, but have a very short range.
• Used between e.g. a smartphone and a smartwatch/wireless earphones.
• Do not require any additional hardware, only the devices themselves, so no additional cost.
• PANs are portable.

Question 5

Network Interface Card (NIC)

Answer 5

• A hardware component that allows a device to connect to a network.
• There are NICs for wireless and wired connection.

Question 6

Switches

Answer 6

A hardware device used to connect several devices on a LAN together.

Question 7

Routers

Answer 7

• A hardware device that transmits data between different networks.
• Used to connect networks to the internet.

Question 8

What is bandwidth?

Answer 8

The amount of data that can be sent across a network in a given time.

Question 9

Cat 5e and CAT 6

Answer 9

• They are common types of ethernet cable.
• Contain pairs of copper wires, twisted together to reduce internal inteference.
• Cheaper than fibre optic cables.
• Decent performance and bandwidth.
• Commonly used in homes and to connect devices on LANs.
• CAT 5e cables have 100Mhz operating frequencies, compared to 250Mhz on CAT 6. So, CAT 6 cables can process more data at the same time.

Question 10

Fibre Optic Cables

Answer 10

• Transmit data as light (photons)
• High performance and expensive cables.
• As they use light, they don’t suffer interference.
• Can transmit data over very large distances at a high bandwidth without loss of signal quality.

Question 11

Coaxial Cables

Answer 11

• Made of a single copper wire surrounded by a plastic layer for insulation and a metallic mesh which provides shielding from outside interference.
• Generally very cheap
• Low bandwidth

Question 12

Benefits of networking computers

Answer 12

1) Sharing files is easier. Network users can access the same files, work on them at the same time, and copy files between machines.

2) Hardware can be shared between devices (e.g. printers).

3) You can centrally install and update software on all computers at once.

4) You can communicate across a network, cheaply and easily (e.g. via email).

5) User accounts are stored centrally, so users can log in from any devices on a network.

Question 13

Drawbacks to networking computers

Answer 13

1) They can be expensive to set up, as you often require extra hardware.

2) Large networks often require employing a specialist to maintain them.

3) Some networks are dependant on one or more servers. If these servers go down, it can be very disruptive for those using the network.

4) Networks are vulnerable to hacking, and malware can easily spread between networked computers.

Question 14

Wireless networks

Answer 14

• Wireless networks use radio waves to transmit data.
• Local wireless networks are called WLANs.
• A Wireless Access Point (WAP) is needed to set up the network. WAPs are switches that allow devices to connect wirelessly.
• Devices need wireless capability to join a network.

Question 15

USB Dongles

Answer 15

Devices that can be plugged into computers that allow them to connect to networks wirelessly.

Question 16

Benefits of using wireless networks

Answer 16

• It’s very simple to add more users to a wireless network. You don’t need any additional hardware.
• They are cheaper and better for the environment, as they don’t require any wires.
• You can add devices like smartphones and tablets to a network.
• They are convenient, as you can automatically connect your device to the network.
• You can move your devices around whilst still being connected to the network.

Question 17

Drawbacks of using wireless networks

Answer 17

• Wireless networks are generally less secure than wired networks, as access points are usually visible to all devices, which can allow hackers to gain access.
• The distance from the WAP, physical obstructions (e.g. walls), and interference from other wireless networks can all reduce signal strength. This means wireless networks have a set range.
• They generally have a lower bandwidth and are less reliable.

Question 18

Star Topology

Answer 18

• All devices are connected to a central switch/server that controls the network.
• Can be wired or wireless.

Question 19

Benefits of using Star Topology

Answer 19

• If a device on the network fails or a cable is disconnected, the rest of the network is unaffected.
• Adding a new device to the network is simple, as you just need one extra cable.
• Higher performance than other topologies, as data from the central device goes straight to the computers.
• This also means there are few data connections compared to other topologies (e.g. bus)

Question 20

Drawbacks of using Star Topology

Answer 20

• In wired networks, every device needs an individual cable to connect to a central switch. This can be expensive for large networks.
• Switches needed for star topologies are expensive.
• Problems with the switch/server disrupt the entire network.
• The maximum number of connects on a network is determined by the switch. It may only have e.g. 10 available ports. You may need to buy a new switch to add more connections.

Question 21

Bus Topology

Answer 21

• All devices are connected to a central cable, called the bus or backbone.
• Two terminators are placed on either end of the backbone cable, to stop data from being reflected. This is important because reflected signals cause interference, and make the network unusable.

Question 22

Benefits of using bus topology.

Answer 22

• Similar to star topology, the network is unaffected if one device fails.
• Bus networks aren’t dependant on a central switch to keep the entire network running.
• They are relatively cheap compared to star networks. The total length of wiring needed is less, and hardware such as terminator/backbone is cheaper buy and maintain than switches.

Question 23

Drawbacks of using bus topology.

Answer 23

• Data collisions are common. Data collisions mean data must be resent, slowing the network down.
• This means bus topologies are unsuitable for large networks.
• If the main backbone cable breaks. the network splits into separate parts, and this can shut down the entire network.
• To try and avoid data collisions, devices must wait for the backbone cable to be available before sending any data. This slows the network down.

Question 24

Network Protocols

Answer 24

A protocol is a set of rules that govern how two or more nodes communicate and how data is transmitted across a network.

Question 25

Layers (TCP/IP Model)

Answer 25

• A layer is a group of protocols that have similar functions.
• Layers are self-contained. Protocols in each later function without needing to know what’s happening in other layers.
• Data can only be passed between adjacent layers. For example, layer 2 can pass data to layers 1 & 3, whereas layer 1 can only pass data onto layer 2.

Question 26

4 layers of the TCP/IP Model

Answer 26

ATIL - Andrew Tate Is Leng

• Application layer: Providing networking services to applications.
• Transport layer: Setting up communications between two devices, and handling the packaging and unpackaging of data.
• Internet layer: Adding IP addresses to data packets, directing them between devices and handling traffic. Used by routers.
• Link layer: Passing data over the physical network. Responsible for how data is sent as electrical signals over cables, wirelessly, and other hardware.

Question 27

Advantages of using layers

Answer 27

• It breaks network communication into manageable pieces. This lets developers to concentrate on only one area of a network, without having to worry about the others.
• Layers are self-contained, so they can be changed without affecting other layers.

-Having set rules for each layer forces companies to make compatible, universal hardware and software, so different brands will work with each other in the same way.

Question 28

Protocols of Application Layer

Answer 28

• HTTP (Hyper Text Transfer Protocol): Used by web browsers to access websites and communicate with web servers.
• HTTPS (HTTP Secure): A more secure version of HTTP, encrypts all sent and received information.
• FTP (File Transfer Protocol): Used to access, edit, and move files between devices on a network.
• IMAP (Internet Message Access Protocol): Used to retrieve emails from a server.
• SMTP (Simple Mail Transfer Protocol): Used to send emails, and also transfer emails between servers.

Question 29

Protocols in the Transport Layer

Answer 29

• TCP (Transmission Control Protocol)
• UDP (User Datagram Protocol)
• They both control the packaging the unpackaging of data.

Question 30

TCP Protocol (Transmission Control Protocol)

Answer 30

• TCP establishes a connection between the sending and receiving devices.
• It splits data into number packets that can be re-assembled into the original data, once they reach their destination (even if they arrive in the wrong order)
• It communicates with the receiving device to make sure that all packets have been transferred correctly. If not, missing/corrupted packets can be resent.
• The sending device receives confirmation when the transfer is complete.

Question 31

UDP Protocol (User Datagram Protocol)

Answer 31

• UDP breaks data down into packets without numbering them.
• They are read by the receiving device in the order they arrive (even if they were sent in a different order).
• UDP only sends each packet once and doesn’t check with the receiving device that everything has been received.
• This saves time, but there’s no way of knowing if packets are lost during transit.

Question 32

When would we use UDP or TCP?

Answer 32

• UDP is suitable for applications that need fast, efficient transmission e.g. live video streams). A slight hiccup in quality is better than a delay in the live stream.
• TCP is better when you need a reliable connection e.g. when downloading files. Missing data packets can cause files to become corrupted and unusable, so this avoids having to redownload an entire file.

Question 33

IP protocol (Internet Layer)

Answer 33

• Establishes connections between routers, and handles network traffic. IP addresses are unique numbers assigned to every device connected to an IP network. They are added to the header of each packet.
• Directs data packets to their destination across the Internet or other IP networks using packet switching.
• Each packet is sent between a series of routers - each router reads the packet’s header, and uses the IP address to decide which network to send the packet too next.
• Packets can take many routes, depending on network traffic.
• Packet switching is efficient as there are so many different routes that packets can take. Packets can arrive quickly, even in heavy network traffic.

Question 34

WiFi protocols (Link Layer)

Answer 34

• WiFi is a family of protocols commonly used in WLANs. Units of data on the link later are called frames, not packets.
• WiFi uses two radio frequency bands, 2.4GHz and 5GHz.
• 2.4GHz has a greater range, and is better at getting through walls, whereas 5GHz is faster over short distances.
• These bands are split into numbered channels that each cover a small frequency range. Channels in 2.4GHz overlap. Overlapping channels can cause interference.

Question 35

How is data encrypted on WiFi networks?

Answer 35

Protocols such as WAP (WiFi Protected Access) encrypt data on WiFi newtorks.