3.5

Question 1

Define Computer Network.

Answer 1

A computer network is a collection of computers linked together to facilitate communication and the sharing of resources.

Question 2

What are some advantages networks?(5)

Answer 2

+ Share resources like printers and scanners
+ Software can be distributed across the network rather than having to install it on each individual computer
+ All files can be backed up centrally
+ Folders and files can be stored on a file server so they can be accessed by authorised users from any computer on the network.
+ Internet connection can be shared and any authorised user on the network can use email.

Question 3

What are some disadvantages of networks?(5)

Answer 3

• If the file server goes down, no one can access their files or do any work.
• Network faults could lead to loss of data
• The larger the network becomes, the more difficult it is to manage; specialist staff may be required
• Viruses may be able to infiltrate the network and infect every computer
• As network traffic increases, performance degrades so accessing resources may become slow.

Question 4

What are the properties of a wired network?(3)

Answer 4

File transfer speeds are generally faster with a wired connection.
Wired connection are not obstructed by walls and ceilings if cables are laid.
Wired tethers user to a single point.
More secure than wireless because they are harder to hack into.

Question 5

What are the properties of a wireless network?(2)

Answer 5

Users can move around freely.
Generally cheaper than wired because no ethernet cables.
Easy to add new devices.
Can be obstructed through walls.

Question 6

Describe a WAN?(3)

Answer 6

A Wide Area Network is a collection of computers and network connected together using resources supplied by a ‘third party carrier’ such as BT.
It uses cables, telephone lines, satellites and radio waves to connect the components which are usually spread over a wide geographical area.
WANs tend to be under collective or distributed ownership and are not necessarily owned by one organisation.

Question 7

Describe a LAN?(3)

Answer 7

A Local Area Network usually covers a relatively small geographical area. It consists of a collection of computers and peripheral devices connected together, often on a single site.
For example, schools may use a LAN connecting the computers in the buildings across the site.
A LAN is usually owned and managed by a single person or organisation.

Question 8

Describe a PAN?(2)

Answer 8

A Personal Area Network is a computer network used for data transmissions among devices such as computers, cell phones and laptops.
The most common kind of technology used in a wireless PAN is Bluetooth, which uses short-range radio waves over distances up to roughly 10 metres.

Question 9

What are routers and switches?(2)

Answer 9

A switch is a component of a LAN that knows the MAC dresses of each individual device connected to it locally. Its function is to send the packets only to the intended recipient, using its MAC address.
A router is designed to route data packets across a WAN such as the internet. Packets are passed from router to router to their destination. If a packet is routed for a computer in a LAN it will be routed to a switch.

Question 10

Purpose of a NIC?(2)

Answer 10

Network Interface Card. Required to connect any network-enabled device. It contains MAC address. Has either a wired connection using an Ethernet cable or a wireless connection.
All devices that can connect to a network have a NIC.

Question 11

Purpose of a MAC address?(2)

Answer 11

Media Access Control address. Each Network Interface Card has a MAC address assigned to it. by the manufacturer. A computer may have more than one MAC address, one for wire Ethernet and one for wireless.
A MAC address is a 48-bit address written as 12 Hex numbers - the first 6 identify manufacturer, and the next 6 are unique to the device.

Question 12

Purpose of an IP address?

Answer 12

When connected to a network each device is given a unique IP address. Routes the individual packets from source to destination via routers.

Question 13

What is a wireless access point?

Answer 13

Uses a radio transceiver to allow wireless connections to a network.

Question 14

What is a packet?

Answer 14

A small unit of data, contains a header contains:
IP address it is going to, and the IP address it has come from
Sequence number
Total number of packets in transmission
Error checking data

Question 15

What is packet switching?

Answer 15

Packets are usually sent to their destination along different routes, and then reassembled in the right order when they arrive. This is packet switching.

Question 16

What are the differences between Star Networks and Bus Networks?(3)

Answer 16

Bus Networks are much cheaper than Star Networks.
Bus Networks also don’t rely on a central node.
Star Networks have more consistent performance and security - data is received only by the node for which it is intended.
Star Networks are also much quicker than bus networks as more devices are added.
Star Networks are easier to manage because cable failures are hard to isolate on Bus Networks.
Star Networks continue to function if one cable fails, but in Bus Networks if one cable fails, the whole network is affected.

Question 17

What is TCP?(2)

Answer 17

Transmission Control Protocol is the standard internet protocol for sending files and documents.
It guarantees that all information will be sent to the recipient in a trade off for speed.

Question 18

What is UDP?(2)

Answer 18

User Datagram Protocol is similar to TCP, but because messages are sent in chunks instead of packets it is often faster, allowing for gaming or video calls over the internet.
UDP transmission also maintains an open connection between the sender and the recipient for the duration of communication, this two-way communication is what makes it faster.

Question 19

What is FTP?(2)

Answer 19

File Transfer Protocol governs the transmission of files across a network and the internet.
FTP uses separate control and data connections between the client and server
as

Question 20

What is SMTP?(2)

Answer 20

Simple Mail Transfer Protocol governs the sending of email messages between servers.
After they are sent to one server to another the messages can then be retrieved using IMAP.

Question 21

What is HTTP and HTTPS?(2)

Answer 21

Hypertext transfer Protocol (secure) is used for accessing and receiving web pages in the form of HTML.
HTTPS includes secure encryption of the information so that it cannot be understood if it is hacked by a hacker. Banks use HTTPS.

Question 22

What is IMAP?(2)

Answer 22

Internet Message Access Protocol governs retrieving emails from email servers.
Emails are stored on a server but IMAP allows users to view and manipulate the messages as if they were stored locally on their own computers.

Question 23

What is IP?(2)

Answer 23

The IP protocol identifies the location of a device on the Internet and routes the individual packets from source to destination via routers.

Question 24

What are the four layers of Network?(4)

Answer 24

Application layer - HTTP(S), FTP, SMTP, IMAP operate here.
Transport layer - TCP, UDP operate here.
Internet layer - IP operates here
Link layer
Internet.

Question 25

What are the functions of all of the four Network Layers?(4)

Answer 25

Application - Where network applications or user software operates.
Transport - This layer sets up the communication between the two hosts and
Internet - Adds IP addresses and routes the packets across the network. May also provide error checking.
Link - This is where the network hardware such as the NIC is located. Operating system device drivers also sit here.

Question 26

What is Ethernet?(3)

Answer 26

Ethernet refers to a family of networking rules or protocols widely used in LANs. It describes how devices should format data ready for transmission between computers on the same network.
Nodes will wait until the connection is quiet before attempting to transmit. If two nodes attempt to transmit simultaneously, they will both stop and wait a random period of time each before reattempting.
Ethernet systems divide data into frames, similar to internet packets. Each frame contains source and destination MAC addresses and error checking data.

Question 27

Describe how Authentication keeps a network secure?(3)

Answer 27

In a networked environment, many of the computers are used by more than one person. The easiest way to stop unauthorised access to your computer or files is to use a combination of a username and password.
Passwords should be ‘strong’ so they are not easy to guess, and for additional security - accounts may be locked after a certain number of failed attempts.
Forms of biometrics such as Face ID or Fingerprint ID are also used because these are obviously hard to replicate.

Question 28

Describe how Encryption keeps a network secure?(3)

Answer 28

Encryption is used to protect data and prevent it being hacked or accessed illegally. For example, people that use online shopping sites will have to type in their payment details, credit card and debit card numbers.
This information needs to be kept safe from anyone trying to intercept the transmission(hackers). Encryption can’t prevent hackers from trying, but it does make the data unreadable.
Encryption uses an Encryption Algorithm to turn plaintext into cipher text. The mathematical formula used to decrypt or encrypt is called the key.

Question 29

Describe how Firewall keeps a network secure?(2)

Answer 29

A firewall is a network security device that monitors incoming and outgoing network traffic and decides whether to allow or block specific traffic based on a defined set of security rules(which you can adjust).
Operating systems like MS Windows have firewall utilities built in but firewall software can also be bought separately.

Question 30

Describe how MAC Address Filtering keeps a network secure?(2)

Answer 30

Every computing device has a unique MAC address, and so it is possible to use MAC filtering a wireless network to determine which devices are allowed access to the network.
The weakness of this is that while is identifies the permitted devices, it can not identify which individual is using a device.

Question 31

Describe how User Access Levels keep a network secure?(2)

Answer 31

User Access Levels should be set for disks, folders and files so users can only access what they need to. At schools for example, lots of students will have Read-Only access on lots of files, where teachers may have Read-Write access.
Lots of files and folders may not even be viewable to students. The Data Protection Act stipulates that employers must keep personal data secure so setting appropriate access rights is a legal responsibility.

Question 32

What is Wi-Fi?(3)

Answer 32

Wi-fi is the name for the technology that allows electronic devices to connect to a wireless LAN(WLAN). Wi-fi devices connect to the internet via a wireless LAN and a WAP(Wireless Access Point).
The WAP receives data from a network via its physical connection, the transmitter then converts this data into radio waves which are then transmitted.
Any device on the network receives this radio signal via a Wi-Fi adaptor which allows it to communicate or download data from the data source.

Question 33

Describe how MAC Address Filtering keeps a network secure?(2)

Answer 33

Every computing device has a unique MAC address, and so it is possible to use MAC filtering a wireless network to determine which devices are allowed access to the network.
The weakness of this is that while is identifies the permitted devices, it can not identify which individual is using a device.