Computer networks, connections and protocols

Question 1

Network

Answer 1

A network is two or more devices connected together with the purpose of sharing resources.

Question 2

Advantages of networks

Answer 2

Users can share resources such as printers and connections to the internet.
Users can access their files from any computer on the network.
Communication can be made easier via email and social networks.
Users can share files and folders such as central databases and spreadsheets.
Servers can be used to provide centralised backups, updates and security.

Question 3

Disadvantages of networks

Answer 3

There are increased security risks to data.
Malicious software can infiltrate the network and render it unusable.
Servers and switches can provide a central point of failure, resulting in users not being able to complete tasks using their computer.
Factors can impact the performance of the network such as the number of users and data on the network at one time.

Question 4

Local area network (LAN)

Answer 4

A local area network is a network which has a small geographical area. All of the hardware is owned by the company / organisation / household.
LANs use unshielded twisted cables, fibre optic cables or wireless connections (Wi-Fi).

Question 5

Wide are network (WAN)

Answer 5

A wide area network is a network which has a large geographical area. They are a connection of LANs joined together. Computers on a WAN are connected via routers. The hardware used to connect the networks together are not all owned by the same company / organisation / household for example telephone lines. WANs use fibre optic cables, telephone lines and satellite to connect the LANs together.

Question 6

Factors of network performance (number of users)

Answer 6

This is how many users are on the network at the same time. Too many users can cause the network to slow down if there is not enough bandwidth for all of the data being sent and received.

Question 7

Factors of network performance (bandwidth)

Answer 7

Bandwidth is the amount of data that can be sent and received at any given time. it is measured in bits per second. a smaller bandwidth means less data can be sent and the network can slow down, potentially to the point of becoming unusable.

Question 8

Factors of network performance (Latency)

Answer 8

Latency is the delay between data being sent and received. If there is a big delay between the two, more data will be on the network causing collisions. This can lead to even more packets of data being sent as the error rate has increased.

Question 9

Factors of network performance (error rate)

Answer 9

Error rate is the measure of how many packets of data do not reach their destination. An increased error rate occurs in less reliable connections - a poor wireless signal would be a contributing factor to an increased error rate.

Question 10

Factors of network performance (transmission media)

Answer 10

Transmission media is the type of cable used in wired connections. Wired connections offer a higher bandwidth than wireless connections. The main option for transmission media are unshielded twisted pair and fibre optic. Fibre optic has a higher bandwidth than copper cabling as well as faster transfer speeds.

Question 11

Factors of network performance

Answer 11

Bandwidth, Transmission media, Error rate, Number of users and Latency

Question 12

Local area network hardware

Answer 12

Network hardware is a selection of essential components that enable the connectivity and communication of devices within computer networks.
Router, Wireless access point (WAP), Switch, Network interface card (NIC) and Transmission media.

Question 13

Router

Answer 13

The router is responsible for routing data packets between different networks. The router connects networks together. The router can manage and prioritise data traffic, which can help to keep connections stable. The router will assign IP addresses to the devices on the network.

Question 14

Wireless access point (WAP)

Answer 14

The wireless access point allows wireless devices to connect to a local area network. The WAP connects to a switch or hub via an ethernet cable. The WAP range is limited so the use of multiple WAPs can be used for complete complete coverage.

Question 15

Switch

Answer 15

A switch allows multiple wired devices to connect to a local area network. The switch is an active device, which means it can inspect network data and route it to the correct devices, thus reducing traffic on the network. A switch can contain extra software to allow administration and configuration.

Question 16

Network interface card (NIC)

Answer 16

The network interface card is required for a computer to connect to a network. A NIC can be both wired and wireless and allows your computer to send and receive data over a network.

Question 17

Transmission media

Answer 17

Transmission media is the phrase used to describe the method of connecting a wired network.
Unshielded twisted pair (UTP), Coaxial (copper) and fibre optic.

Question 18

Unshielded twisted pair (UTP)

Answer 18

A twisted pair cable is made up of insulated pairs of copper wires twisted around each other. Twister pair is low bandwidth and more affordable than the other two cables, so it is commonly found in local area networks.

Question 19

Coaxial

Answer 19

A coaxial cable is medium bandwidth and more expensive than UTP. Coaxial cables are used to connect large scale networks such as telephone networks and digital cable / satellite television.

Question 20

Fibre optic

Answer 20

A fibre optic cable unlike the other two, is unaffected by electrical noise making it the fastest in terms of data transfer. Fibre optic is high bandwidth and the most expensive. It is commonly used for high data volume networks and long distance connections such as between cities and countries.

Question 21

Internet

Answer 21

The internet is a collection of networks spanning the whole world. The internet is the largest wide area network. The internet is used to provide connectivity and is different from the World wide web, which is a collection of web pages you access via a web browser.

Question 22

How does the internet work

Answer 22

In your home, you have a router. Inside the router is a modem which allows you to connect to your internet service provider (ISP) via a telephone line or fibre optic. An ISP is connected to a domain name system (DNS). This results in other routers also connecting together, forming a large interconnection of networks containing servers, other routers and other LANs. All of these inter connected networks are known as the internet.

Question 23

Domain name system (DNS)

Answer 23

The domain name system is a directory of domain names and is used to translate human readable domain names to the numeric IP addresses that computers use. When you type a Uniform resource locator (URL) into your browser, the DNS translates the domain name into its associated IP address so your computer can connect to the server hosting the website. Without DNS we would have to remember the IP address of every site we want to visit.

Question 24

How does DNS work

Answer 24

1. URL entry
2. DNS query - the web browser sends a query to the DNS server to translate the URL into an IP address.
3. DNS resolver - it checks its cache to see it it has the IP address for the requested domain. If not it is sends the request to the DNS root server.
4. Root server query - The root server directs the resolver to a Top level domain (TLD) server based on the extension of the URL.
5. TLD server query - The TLD server then provides the resolver with with the IP address of the domain’s authoritative DNS server.
6. Retrieve IP address - DNS server responds with the IP address for the requested domain.
7. Request the web page - the web browser sends an HTTP or HTTPS request to the IP address it received.
8. Server response - The server at the given IP address processes the request and sends back the data for the web page.
9. Render the web page - The web browser renders the received data into the web page that you see.

Question 25

Web servers

Answer 25

Web servers are dedicated servers that store web pages / websites and other resources. They have a dedicated IP address to ensure that users can access them 24/7.
The most common web servers in use are Hosting websites and Dealing with client requests.

Question 26

Clients

Answer 26

Clients are end users who make requests of web servers. For example a client may request a webpage such as www.patesgs.org.

Question 27

Hosting

Answer 27

Hosting is the storing of websites, files and other content on servers. The servers need to be accessible by thousands of users and need to be available 24/7.
The servers must be reliable and secure from any form of attack.
The IP address for the server must remain the same so that users can access the website whenever they want.

Question 28

Advantages of the cloud

Answer 28

Content in the cloud can be accessed from anywhere at any time.
Users can use any device to access their content.
Users have a large storage capacity available to them.
Low cost / free to set up and use.
Responsibility for backups and security is with the cloud service provider.
Users can easily collaborate.

Question 28

The Cloud

Answer 28

The cloud is a collection of servers which are used to store data, applications and files over the internet.

Question 29

Disadvantages of the cloud

Answer 29

Accessing content and software is only possible when the user has an internet connection.
Expanding capacity can be expensive f using it across a business.
Vulnerable to security threats such as data leaks and photo leaks.

Question 30

Network topologies

Answer 30

A network topology is the physical structure of the network.
It defines how the network hardware will be arranged to create the network.
Many different topologies have been used in the world of networking however, there are two popular topologies.
Star Topology
Mesh Topology

Question 31

Star Topologies

Answer 31

A star topology has a central switch which all other devices connect to.
A switch is an intelligent device which ensures that traffic only goes to the intended device.
A star topology is commonly seen in most homes, businesses, organisations and schools.

Question 32

Advantages of star topologies

Answer 32

Fast data transfers to the hub as each wire isn’t shared with other computers.
If one cable fails, the other computers are not affected.

Question 33

disadvantages of star topologies

Answer 33

Requires additional hardware such as the central switch and network cables.
If the central switch fails, the whole network fails.

Question 34

Mesh networks

Answer 34

A mesh topology allows all computers to be connected to all other computers
This is known as a full mesh network topology
LANs can make use of mesh networks however, they are more commonly seen in IoT devices such as wearable technology and smart home devices

Question 35

Advantages of mesh networks

Answer 35

No single point of failure - If any single cable stops working, the rest of the network will continue to work as the data can find a different route to get to its destination.

Question 36

Disadvantages of mesh networks

Answer 36

The topology requires a lot of hardware, cables and switches to set up.
This means there is a higher cost for setting up the network
Adding new devices is not as easy as in a star topology, making it more challenging to scale the network.
The solution to these disadvantages is called a ‘Partial Mesh Topology’.

Question 37

Partial mesh networks

Answer 37

A partial mesh topology is very similar to a full mesh, with the difference being that each device is not connected to every other device directly
This means -
Less cables and hardware are required.
Multiple routes still exist between devices.
It is a compromise solution to reduce the amount of hardware needed.

Question 38

Addresses

Answer 38

Devices on a network send and receive data, a device needs an address to ensure it sends data to the correct place
There are two types of network address systems:
IP Address
MAC Address

Question 39

Internet protocol (IP) address

Answer 39

An IP (Internet Protocol) address is a unique identifier given to devices which communicate over the Internet (WAN)
IP addresses are dynamic, they can change.
IP addresses make it possible to deliver data to the right device.
A device connecting to a network will be given an IP address, if it moves to a different network then the IP address will change.

Question 40

IPv4

Answer 40

Internet Protocol version 4 is represented as 4 blocks of denary numbers between 0 and 255, separated by full stops.
Each block is one byte (8 bits), each address is 4 bytes (32 bits).
IPv4 provides over 4 billion unique addresses, however, with over 7 billion people and countless devices per person, a solution was needed.

Question 41

IPv6

Answer 41

Internet Protocol version 6 is represented as 8 blocks of 4 hexadecimal digits, separated by colons.
Each block is 2 bytes (16 bits), each address is 16 bytes (128 bits).
IPv6 could provide over one billion unique addresses for every person on the planet.

Question 42

Media access control (MAC) address

Answer 42

A MAC (Media Access Control) address is a unique identifier given to devices which communicate over a local area network (LAN).
MAC addresses are static, they can never change.
MAC addresses make it possible for switches to efficiently forward data to the intended recipient.
Any device that contains a Network Interface Card (NIC) has a MAC address assigned during manufacturing.
A device connecting to a local network already has a MAC address, if it moves to a different network then the MAC address will stay the same.