1.3 Computer networks, connections and protocols

Question 1

LAN (Local Area Network)

Answer 1

Covers a small geographical area for example, a building or group of buildings

Question 2

WAN (Wide Area Network)

Answer 2

Covers a large geographical area such as many cities or countries

Question 3

What are the factors Affecting the Performance of Networks?

Answer 3

The number of devices on a network can result in slower transmission of data because the bandwidth will be split between all the devices meaning there is less bandwidth for each device. If the maximum bandwidth is used, then devices cannot transmit data.
Error rate
Distance between nodes
The amount of bandwidth available
The mode of transmission e.g. wired/wireless

Question 4

Describe Client-Server Network

Answer 4

Servers are used to provide services for the rest of the network.
Server manages user logins, security, file handling and internet access.
Commonly used to organise a LAN.

Question 5

Describe Peer-to-Peer Networks

Answer 5

Peer-to-Peer networks do not make use of servers
All computers have equal status
Each computer can share files with others
Security can be an issue
Suitable for small home installations

Question 6

Wireless Access Points

Answer 6

Receives data from a network via a physical connection
The transmitter converts this data into radio waves which are then transmitted

Question 7

Routers

Answer 7

Used to connect and receive data from devices
Used to determine the correct destination for data and to forward data to the correct destination
Uses IP Addresses
Connects networks to the Internet
Stores the addresses of devices attached
Maintains a route table
Identifies the most efficient path to the destination
Assigns IP addresses to nodes

Question 8

Switches

Answer 8

Used to connect and receive data from devices
Used to determine the correct destination for data and to transmit data to the correct destination
Uses MAC Addresses
Connects nodes/Computers
Looks for correct addresses before sending data

Question 9

NIC (Network Interface Card)

Answer 9

Required to connect any network-enabled device
A physical component which can operate wirelessly or have a wired connection

Question 10

Transmission Media

Answer 10

A standard network cable is referred to as an Ethernet cable which uses twisted-pair copper cabling or fibre optic cabling.
Connecting computers with copper cable is cheaper than fibre optic.

Question 11

Fibre optic cable

Answer 11

Fibre optic cable has a much greater bandwidth than copper coaxial cables or twisted-pair copper cables, transmission is faster, and cables do not break easily.
Fibre optic cables won’t be affected by electromagnetic interference whereas copper cables can interfere with other wires and cause a loss in data transmission.
Fibre optic transmission is unlikely to need to be boosted whereas transmission via copper cable frequently needs boosted using a repeater.

Question 12

Copper coaxial cable

Answer 12

Copper coaxial cable is used for cable TV and broadband and in some places where fibre optic is unavailable. Coaxial cables transmit data very quickly and over large distances. There is less distortion or interference in comparison to twisted-pair cables as coaxial uses better shielding.

Question 13

Twisted-pair copper cable

Answer 13

Twisted-pair copper cable is commonly used to connect devices on a LAN because it is lightweight, inexpensive, and easily installed.

Question 14

How is the DNS (Domain Name Server) used?

Answer 14

A user enters a Uniform Resource Locator (URL) into a web browser. The web browser sends a request to the Domain Name Server for the matching IP address. If found, the IP address is returned. A request is then sent to the IP address for the website.

Question 15

What does DNS stand for?

Answer 15

Domain Name Server

Question 16

What is web hosting?

Answer 16

A company that can store your files and make them available to you from other internet enabled devices.
Services of a hosting company include hosting website pages, images and related files, online file hosting and video hosting services such as YouTube.
Web hosting often includes Domain Name Registration which ensures that the name chosen for the website has not already been taken, and if it is acceptable, is then registered and made available on the DNS.

Question 17

What is cloud storage?

Answer 17

Cloud storage refers to saving data in an off-site storage system maintained by a third party e.g. Google, Dropbox or Microsoft.
Instead of saving data on your computer’s hard drive or other local storage device, you save it to a remote storage facility, and access it via the internet.

Question 18

What are the advantages of cloud storage?

Answer 18

Data can be accessed from anywhere in the world where there is an internet connection
Data can be shared with people in different locations
Backup is no longer an issue as it is the responsibility of the provider to keep the data safe
Cloud based servers enable access to software on demand meaning that instead of having the software installed on a local machine, you can access the software from any internet-enabled computer

Question 19

What are the disadvantages of cloud storage?

Answer 19

You are dependent on having an internet connection to access your data
Some users are concerned about security in the cloud and whether their data could be accessed by a hacker.

Question 20

What is the purpose of a Web Server?

Answer 20

A website is hosted on a web server

Question 21

What is a client?

Answer 21

The computers that access websites are called clients

Question 22

Star Topology

Answer 22

All nodes are connected to a central switch or hub
Star networks tend to be fast and reliable since each device has its own connection to the central server
Minimal data collisions

Question 23

Mesh Topology

Answer 23

Uses direct connections between the nodes
Each node has multiple connections via other nodes to each other node
A full mesh has direct connections between each node
A partial mesh has one node connected to all the others with additional connections between some of the nodes
There is no need for a central switch
Having no central switch means there is no single point of failure
Data can be sent directly between nodes or can be routed via other nodes
The ability to send signals via multiple paths makes the mesh a reliable topology but the number of connections makes the topology very expensive and complex to set up

Question 24

Wired Connection (Ethernet)

Answer 24

Ethernet is used by most manufacturers to allow compatibility with other devices
Ethernet has a high bandwidth
Ethernet has inbuilt security
Ethernet is a proven/reliable connection
Ethernet is low cost for purchase/installation and maintenance compared to other wired connections

Question 25

Wireless Connection (Wi-Fi)

Answer 25

Wi-Fi is a family of protocols that make wireless networking possible.

Question 26

Wireless Connection (Bluetooth)

Answer 26

Radio wave technology designed for communicating over short distances of up to 100 metres but typically no longer than 10 metres
Bluetooth devices commonly have built-in radio antennas so that they can send and receive signals from other Bluetooth devices.
Some Bluetooth devices without built-in antennas can work with a Bluetooth plug-in adapter.
Bluetooth can be used commonly for connecting a mouse wirelessly to a laptop or PC, downloading photos from a phone or digital camera between devices, linking a hands-free headset to a smartphone or connecting wirelessly to devices such as speakers and headphones to play music without being connected by a cable.

Question 27

Encryption

Answer 27

Data cannot be understood if it is intercepted post encryption
Only authorised users can access confidential information
Follows guidance provided by the Data Protection Act

Question 28

IP Addressing

Answer 28

A protocol used to identify the location of a device on the internet
Routes the individual packets from source to destination via routers
Set by the ISP (Internet Service Provider)

Question 29

MAC Addressing

Answer 29

Set by the manufacturer
Identifies the physical location of a device’s network interface card uniquely on a LAN

Question 30

Standards

Answer 30

Allow hardware and software to interact across different manufacturers
Provide rules for different areas of computing such as cabling, ethernet and connectivity

Question 31

TCP/IP (Transmission Control Protocol/Internet Protocol)

Answer 31

Consists of two separate protocols, TCP and IP
TCP is a standard that defines how messages are broken up into packets and reassembled at the destination. It also detects errors and resends lost packets.
IP is protocol used to identify the location of a device on the internet and routes the individual packets from source to destination via the router.

Question 32

HTTP (HyperText Transfer Protocol)

Answer 32

Used for accessing and receiving web pages in the form of HTML files on the Internet.
The protocol requests the web server o transmit the requested web page to the user’s browser for viewing.

Question 33

HTTPS (HyperText Transfer Protocol Secure)

Answer 33

Used to access websites securely
Encrypts the information so that it cannot be understood if it is hacked.

Question 34

FTP (File Transfer Protocol)

Answer 34

Standard network protocol used when transferring computer files between a client and server on a computer network.
FTP is based on a client-server model and uses separate control and data connections between the client and the server.

Question 35

POP (Post Office Protocol)

Answer 35

Receives and holds email for an individual until they pick it up
Creates local copies of emails and deletes the originals from the server meaning the emails are tied to the specific device and can be viewed offline.

Question 36

IMAP (Internet Message Access Protocol)

Answer 36

An email protocol that stores email messages on a server but allows users to view and manipulate the messages as though they were stored locally on their own computers
Users can organise the messages into folders, flag messages as urgent and save draft messages on the server.
Allows simultaneous access by multiple clients
More suitable than POP if you are going to access your email from different devices or if your messages are managed by multiple users.

Question 37

SMTP (Simple Mail Transfer Protocol)

Answer 37

Used to send emails between servers
Most email systems that send mail over the internet use SMTP to send messages from one server to another
Messages can be retrieved with an email client using either POP or IMAP
Users typically use a program that uses SMTP for sending email and either POP or IMAP for receiving email.

Question 38

The Concept of Layers

Answer 38

TCP/IP model consists of four layers, creating a modular design with each layer responsible for a small part of the communication process
The division of network protocols and services into layers helps simplify networking protocols by breaking them into smaller, more manageable units, and also offers greater flexibility. By dividing protocols into layers, protocols can be designed to work on any device, regardless of operating system.