Networks part 2

Question 1

Largest WAN

Answer 1

The internet

Question 2

WHAT IS THE INTERNET

Answer 2

The internet is a collection of interconnected networks spanning the world

The concept of the Internet as a network of computer networks

Question 3

Difference between internet and world wide web

Answer 3

The internet is NOT the same as the “World Wide Web” which is just a service on the internet

The internet itself is just the hardware, the cables, the wireless connections and the routers that make the internet what it is

Question 4

A Domain Name service role in the conversion of a URL to an IP address

Answer 4

1. URL request by browser made from user e.g. www. bbc.co.uk
2. The browser sends the domain name to a domain name server
3. The DNS maps the domain name to an IP address and returns it to the browser
4. GET request for the webpage / resource is sent to the web server using the IP address
5. Requested webpage/resource is returned to the clients web browser

Question 5

Why are web addresses used instead of IP addresses

Answer 5

When you request a page on a server, you would need to refer to its IP address.

This is not very convenient for humans as we are not very good at remembering sequences of numbers – we prefer to use words

Web addresses which are easier for humans to remember are converted to IP addresses for routers by a Domain Name Service (DNS) revolver server

Question 6

What is domain name service made up of

Answer 6

A Domain Name Service (DNS) is made up of multiple Domain
Name Server

Question 7

What do servers do

Answer 7

Servers provide services

(e.g. Web server -> Web pages, File server -> file storage/retrieval)
E.g.

Clients request/use services from a server

Question 8

Purpose of the cloud

Answer 8

Severs can be used to store data and programs remotely that can be accessed and used over The Internet

This is known as ‘The Cloud’ or ‘Working in the Cloud’

Question 9

Advantages of The Cloud (storage) (rather than storing data and programs on your PC):

Answer 9

Access information any time

Access information anywhere

Access information from any device

A large storage capacity

Automatic backup of data

Easy online collaboration

No need to buy expensive hardware or store data or run complex applications

No need to pay IT staff to manage the hardware

They provide access to anything, anywhere, automatic backup and collaboration of document

Question 10

Disadvantages to the cloud

Answer 10

Need connection to the Internet to access files or applications
Dependent on host for security and back ups
The hosting company could be targeted by online hackers - data stored in the cloud can be vulnerable to hackers

Subscription fees for using cloud storage and software may be expensive

Download and upload speeds can be affected by the internet connection

Question 11

What is hosting

Answer 11

Hosting is when a business uses its servers to store files of another organisation
_____________________________
Websites are stored on servers dedicated for this purpose
This is known as hosting

Hosted solutions provide 24/7 access, multiple users and greater security

Question 12

Types of network topologies

Answer 12

Star network topology
Full/partial mesh network topology

Question 13

What is a network topology

Answer 13

A given arrangement of all the elements you need for networking.

Question 14

What is a star network topology

Answer 14

Type of network topology where:

Includes a central switch

All devices connect into the central switch

The switch is intelligent and makes sure traffic only goes where it is intended

Question 15

Advantages of star network topologies

Answer 15

If a single cable breaks only that computer (connected to the switch) is affected. (if one link fails, all the other devices will continue to operate)

There will be less network traffic and fewer collisions

Adding or removing devices is easy and can be done without affecting the entire network

Data can be directed to the intended node directly without having to pass along the complete network

Question 16

Disadvantages of star network topology

Answer 16

Network operation depends on the functioning of the central component (file server or switch0 - if this fails, then so will the entire network

It requires a lot of cables as each computer is connected individually to the central component and so will be expensive

Question 17

What is the mesh topology

Answer 17

Each of the network nodes, servers, client computers and printers are interconnected with one another

Every node not oly sends its own signals but also relays data from other nodes

Every node is connected to ever othe rnode

Question 18

Advantages of mesh topology

Answer 18

Data can be transmitted from different devices simultaneously

Even if one of the components fails there is always an alternative route for the data

It can handle high volumes of data traffic

Adding more devices will not hamper the transmission of the data as all nodes help to transmit the data

Question 19

Disadvantages of network topology

Answer 19

The overall cost is expensive compared with other topologies since there is a lot more cabling and switch hardware required

Very difficult to manage as it requires continuous supervision

Disadvantage is that there is a lot more cabling and switch hardware are required which will add to the cost (be expensive and impractical) for large networks

Question 20

Example of a wired connection

Answer 20

Ethernet

Question 21

Advantages of Wired networkds

Answer 21

Very high bandwidth up to 100 Gbps
Security is good. A user has to physically plug their computer into the network using a cable
There should be no interference with the signal on a network cable

Question 22

Disadvantages of of wired network

Answer 22

Setting up is more difficult. Cables have to be run all over the site

Not very mobile. A user has to plug the computer into a wall socket and cannot use it in a room without one. Contact ids lost as soon as it is unplugged if the user wants to move to another room

Question 23

Advantages of wireless networks

Answer 23

Installation is easy. All that is needed are wireless access points and NICs for any computers such as desktop computers, that do not have them build in

Cost. Cheap. Just cost of wireless access point

Very mobile. Users can access the network from anywhere on the site. Can move from room to room and remain connected

Question 24

Disadvantages of wireless networks

Answer 24

Far lower bandwidth. The latest version of Wi-Fi can offer speeds from 433Mbps to 2 or 3 Gbps. Compared to speeds of up to 100 Gbps for wireless networks

Security is poor. Anyone within range can see the network and connect to it to use it. The access point must be secured with a security password. Some form of encryption must be set up

Interference: The signal can be affected by walls and electronic equipment such as microwave ovens. It is also affected by distance from the access point and the number of connected devices.

Question 25

What is etherenet

Answer 25

Ethernet is a standard for networking technologies

Used for communicating on a wired local area network

Provides reliable, error free, fast communication between two points

Includes a number of associated protocols (rules for governing communications)

Question 26

disadvantage of ethernet/wired connections

Answer 26

A user’s location is limited by the need for a physical cable connection.

A set up relying on Ethernet relies on lots of cables, connections, ports and physical hardware which will affect (the overall) cost (of the network)

Question 27

Features of bluetooth

Answer 27

Bluetooth is another, more modern standard for wireless networking:

It is ideal for connecting personal devices e.g. Bluetooth enabled headphones to connect to a mobile

It has a very short range, around 10 metres

It has a very low power consumption compared to Wi-Fi

Bluetooth –
range - 10 metres

Bandwidth – Low

Power consumption - Low

Question 28

Features of wifi

Answer 28

Wi-Fi is a common standard for wireless networks:

Users can move around freely

Easier to set up, and less expensive (than wired networks)

Convenient to use

Can handle large numbers of users

Transfer of information to social media is much easier

Speeds are slower than wired networks

Relies of signal strength to the wireless access point (WAP)

Signal can be obstructed

Less secure than wired networks

Wi-Fi

Range – 100 metres

Bandwidth – High

Power consumption – High

Question 29

Describe encryption on wireless networks

Answer 29

Wireless networks broadcast data, so it must be encrypted to be secure

This is done by scrambling the data into cipher text using a “master key” created from the SSID (Service Set Identifier) of the network and the password

Data is decrypted by the receiver using the same master key, this key is not transmitted

It is important that the master key is not transmitted at all, because any device listening in would then be able to decrypt the data as well.

Protocols used for wireless encryption include WEP, WPA, WPA2

Both the transmitter and the receiver agree which protocol is being used, and this is normally set when you set up your wireless network.

A handshaking protocol is used to ensure that the receiver has a valid master key before transmission to the device begins

Network protocols are a set of rules outlining how connected devices communicate across a network to exchange information easily and safely.

Question 30

Describe encryption on wired networks

Answer 30

In a similar method to that shown for wireless, basic encryption involves the sender using an encryption key to turn a plain text message into cypher text before sending it out onto the network.

At the receiving device, a decryption key is used to turn this cypher text back into the original.

This form of encryption is known as symmetric encryption