Networks

Question 1

What is a network

Answer 1

When several computers are connected together, to share files / software / an internet connection, peripherals and processing power.

Question 2

what is it called when a computer is not connected to a network

Answer 2

Stand Alone

Question 3

What is a wide area network

Answer 3

the internet is an inter-connected network of networks. it is an example of a wide area network
-covers a large geographical area
-the infrastructure is owned by the organisation

Question 4

What is a Local Area Network (LAN)

Answer 4

-A network that covers a small geographical area
-Typical the infrastructure is owned by the organisation

Question 5

What is the backbone

Answer 5

A backbone or core network is a part of a computer network which interconnects networks, providing a path for the exchange of information between different LANs or subnetworks.

Question 6

what is a IP (internet protocol) address

Answer 6

All devices connected to a network have an IP address
-Uses IPv4 which could hold 4.3billion addresses
-this was ok when the internet first started
-IPv6 is looking to solve this

Question 7

What happens when you type a url into a browser

Answer 7

The request is sent a DNS (Domain Name System) Server to look-up the IP address of the server that is hosting the website

Question 8

What is an internet registry ?

Answer 8

allows individuals to register domain names (website addresses) and adds them to the DNS index

Question 9

What is a Switch

Answer 9

A device that connects computers together on a LAN. A switch onl forwards traffic to the intended recipient

Question 10

what is a hub

Answer 10

A device that connects computers together on a LAN. A hub forwards traffic to all connected computers

Question 11

What is a gateway?

Answer 11

When two types of networks join, e.g. LAN to WAN

Question 12

What is a WAP?

Answer 12

Wireless access point so that WIFI devices can connect to a network

Question 13

What is a router

Answer 13

-Acts as WAP, a hub and a gateway in a house
-a node on a WAN that forwards network traffic along the most appropriate route

Question 14

What is a bridge

Answer 14

Join two LANs together

Question 15

what is a NIC

Answer 15

Network interface card- traditionally a NIC was separate card to connect an ethernet cable

Question 16

What is circuit switching

Answer 16

involves creating a complete dedicated physical connection between two endpoints

once used for the telephone networks but is not practical for the billions of devices that connect to the internet today

Question 17

What is package switching

Answer 17

When data is split into equal sized “packets” and transferred over a network. Each packet can take it’s own independent route

if one packet arrives corrupt, that single packet can be re-sent rather than the whole file

Question 18

What is latency

Answer 18

the amount of time it takes for a packet to reach its destination

Question 19

what is badwidth

Answer 19

the amount data that can be transferred within a set time period. E.g. per second

Question 20

What is a router

Answer 20

A router forwards packets from one network to another. Routers look at the destination IP address of a packet and forward on the most appropriate link. Each transfer is called a hop

Question 21

What is a packet made up of

Answer 21

each packet is kept small

Header - sender’s IP / Recipient’s IP, protocol, packet number and hop count

Payload - data

Trailer - error checking. A check sum is a value that is sent with the payload. when some maths is done, if the answer is the same the sent checksum then we assume that the data is not corrupt

Question 22

What are protocells

Answer 22

Are a series of rules that computers follow when communicating

Question 23

What is HTTP

Answer 23

Hyper Text Transfer Protocol - is for transmitting and receiving small files e.g. HTML, CSS, JS, JPGS

Question 24

What is FTP

Answer 24

File Transfer Protocol - is more appropriate for transferring large files

Question 25

what is HTTPS

Answer 25

Encrypted version of http

Question 26

What is SMTP

Answer 26

Simple Mail Transfer Protocol for sending Emails

Question 27

What is TCP and UDP

Answer 27

Requires packets to be ordered, received no errors and are confirmed by recipients. UDP packets are just received, any corrupt packets are just delt with and there is no conformation

Question 28

What is TCP/IP Stack

Answer 28

There are 4 layers to the TCP / IP stack which is used to transfer packets over a network

Question 29

What is the application layer

Answer 29

The software that wants to transmit data to another computer uses the application layer to select an appropriate protocol

Question 30

What is the transport layer

Answer 30

Uses TCP to split data into packets and numbers them. Adds the port number to the header according to the protocol.
When a device receives a packet, this is when it is re-ordered, checked for errors and acknowledged

Question 31

what is the internet layer

Answer 31

The IP address of the sender and recipient are added to the header of each packet.

Question 32

What is the link layer

Answer 32

The IP address of the sender and recipient are added to the header of each packet

Question 33

what are the 4 layers of the tcp stack

Answer 33

application layer, transport layer, internet layer & link layer

Question 34

What is a firewall

Answer 34

A firewall can be hardware or software

It prevents unauthorised network from incoming and outgoing through the firewall

A computer has a number of ports, lots of different kinds of network traffic arrives at certain ports. E.g. port 80 is HTTP traffic

the firewall listens to these ports and inspects traffic

Question 35

What is packet filtering

Answer 35

A firewall technique is where the IP address of each packet is inspected to check if its “allowed”

if the packet is allowed, the port is opened for the duration of the transfer and closed again after.

Question 36

What are proxy servers and VPN’s

Answer 36

A proxy server is a computer in another location that forwards on web requests on your behalf. Responses (Files / streaming Video) are sent to proxy, who forward it on to you - This hides your true location and make your computer anonmous on a network

A VPN also encrypts data

Question 37

What are the features of a proxy server

Answer 37

-Anonymise location
-Filter content (handy in a school / collage)
-Log all web requests with your user ID
-Keep a cache of frequently visited websites

Question 38

What should the proxy server do if website update occurs

Answer 38

If an update occurs to a website, the proxy server should check the Data/time of cached vs homepage so that a stale website isn’t sent to the requesting computer

Question 39

What is malware

Answer 39

A general term for software written by someone with malicious intent, such as to corrupt data / collect personal information covertly

Question 40

What is a virus

Answer 40

Malicious software that corrupts files on your computer. Requires a human to help spread

Question 41

What is spyware

Answer 41

When software sends a key log and files to attacker

Question 42

What is a Trojan

Answer 42

malware disguised as legitimate software. Users open unwittingly thinking they’re installing reputable software

Question 43

What is a worm

Answer 43

Same as a virus, but can spread over a network

Question 44

What is Phishing

Answer 44

Attackers send emails impersonating companies trying to et victims to click a link to website clone and enter personal data

Question 45

What is buffer overflow

Answer 45

Buffer overflow occurs when a program accidently writes data to a location too small to handle it

• As a result, the overflowed data (written to location #3 below) may end up in a neighbouring instruction space
• Malware can deliberately cause and manipulate overflow data which may then be read as malicious ‘instruction’

Question 46

What is SQL injection

Answer 46

A malicious user can enter SQL commands via online database forms to change the processing