Topic 5 - Fundamentals of computer networks

Question 1

Define what a computer network is.

Answer 1

A network is two or more computers or other electronic devices that are connected together for the purpose of communication.

Question 2

What are the benefits and risks of a computer network?

Answer 2

Advantages:
computers can share resources e.g printers
Files can be accessed through any computer in the network.
Data easy to back up.
Risks:
Network hardware is expensive
Viruses may be able to infiltrate the network and infect every computer.

Question 3

Describe the main types of computer network including:

Personal Area Network (PAN)
Local Area Network (LAN)
Wide Area Network (WAN).

Answer 3

PAN – only Bluetooth needs to be considered.
LAN – usually cover small geographical areas.
are often owned and controlled/managed by a single person or organization.
WAN - The Internet is the biggest example of a WAN.
usually cover a wide geographic area.
are often under collective or distributed ownership.

Question 4

What types of cable does wired networks use?

Answer 4

Fibre and copper

Question 5

What are the advantages and disadvantages of wireless networks?

Answer 5

Advantages:
new nodes can easily be added
users can move around freely and still stay connected
Disadvantages:
Radio signals have a limited range.
Each wireless access point (WAP) only has so much bandwidth to share among connected nodes.
Radio signals can suffer from electromagnetic interference from other devices and even other radio signals.

Question 6

What are the advantages and disadvantages of wired networks?

Answer 6

Advantages:
faster data transfer compared to wireless networks
less likely to suffer from interference than wireless networks
difficult for unauthorized users to intercept data
Disadvantages:
they are expensive to install or reconfigure
users can’t instantly move a device from one location to another as there may not be a network connection available

Question 7

Explain the following common network topologies:
star
bus.

Answer 7

Star topology is a topology in which all devices are connected to a central hub. Bus topology is a topology where each device is connected to a single cable known as the backbone.

Question 8

Define the term ‘network protocol’.

Answer 8

an established set of rules that determine how data is transmitted between different devices in the same network

Question 9

Explain the purpose and use of common network protocols including:

Ethernet

Answer 9

describes how devices should format data ready for transmission between the computers (nodes) on the same network.
Ethernet systems divide data into frames, and frames detected to contain transmission errors are dropped or resent.

Question 10

Explain the purpose and use of common network protocols including:

Wi-Fi

Answer 10

Wi-Fi uses Internet Protocol (IP) to communicate between endpoint devices and the LAN. allows devices to access the internet.

Question 11

Explain the purpose and use of common network protocols including:

TCP (Transmission Control Protocol)

Answer 11

breaks up messages sent over the internet into packets. reassembles packets of the other end, detects errors, and resends lost messages.

Question 12

Explain the purpose and use of common network protocols including:

IP (Internet Protocol)

Answer 12

Routes individual packets from one IP Address to another.

Question 13

Explain the purpose and use of common network protocols including:

HTTP (Hypertext Transfer Protocol)

Answer 13

HTTP (hypertext transfer protocol) - used for accessing and receiving web pages via internet

Question 14

Explain the purpose and use of common network protocols including:

HTTPS (Hypertext Transfer Protocol Secure)

Answer 14

HTTPS (Hypertext Transfer Protocol Secure) encrypts the information so that it cannot be understood by an eavesdropper.

Question 15

Explain the purpose and use of common network protocols including:
FTP (File Transfer Protocol)

Answer 15

used for sending or retrieving to or from a FTP server

Question 16

Explain the purpose and use of common network protocols including:
SMTP (Simple Mail Transfer Protocol)

Answer 16

used for sending emails (email protocol)

Question 17

Explain the purpose and use of common network protocols including:
IMAP (Internet Message Access Protocol).

Answer 17

IMAP (internet message access protocol) will leave messages on a server. can be accessed by multiple devices and only removed if user deletes them.

Question 18

Explain the following methods of network security:

authentication

Answer 18

checking that the computer and the user are allowed to access content

Question 19

Explain the following methods of network security:

encryption

Answer 19

encoding of data so that it can no longer be easily understood

Question 20

Explain the following methods of network security:

firewall

Answer 20

firewall will detect packets from malicious computers.
Separate a trusted network from an untrusted network (normally the Internet)
Data is sent around a network in small packets of information

Question 21

Explain the following methods of network security:

MAC address filtering.

Answer 21

A Media Access Control (MAC) is a unique hex number assigned to all Network Interface Cards
allows devices to access, or be blocked from accessing a network based on their physical address embedded within the device’s network adapter.

Question 22

Describe the 4 layer TCP/IP model:

application layer

Answer 22

Application layer: where network applications, such as web browsers or email programs operate.

Question 23

Describe the 4 layer TCP/IP model:

Transport layer

Answer 23

The Transport layer creates the connection between two computers, or ‘hosts’

Question 24

Describe the 4 layer TCP/IP model:

Internet layer

Answer 24

addresses and packages data for transmission. Routes the packets across the network.

Question 25

Describe the 4 layer TCP/IP model:

Link Layer

Answer 25

where the network hardware such as the NIC (network interface card) is located. OS device drivers also sit here.

Question 26

what layer does HTTP, HTTPS, SMTP, IMAP and FTP operate at?

Answer 26

Application layer

Question 27

what layer does TCP and UDP protocols operate at?

Answer 27

transport layer

Question 28

what layer does the IP protocols operate at?

Answer 28

internet layer

Question 29

what is WI-FI?

Answer 29

A family of related protocols. Wi-Fi is a trademark and that the generic term for networks of this nature is WLAN.

Question 30

what is ethernet?

Answer 30

a family of related protocols.

Question 31

list advantages and disadvantages of star topology

Answer 31

advantages:
fast data transfer to hub as each wire isn’t shared with other computers
if one cable fails other computers are not affected
disadvantages:
requires additional hardware such as central switch and network cables
if central switch fails, whole network goes down

Question 32

list advantages and disadvantages of bus topology

Answer 32

advantages:
less cable so cheaper to install network
easier to add more devices
disadvantages:
if cable is damaged, whole network fails
single cable is shared by many devices so many collisions of data if sent at same time
any device can view all data on cable creating security risk.

Question 33

describe one difference between a PAN and a LAN (1 mark)

Answer 33

PAN’s have one user, LANs normally have more than user.