Networks

What is a LAN?

Local Area Network

Small geographical area

Hardware owned by organisation

Give an example of a LAN.

Home/office/school network

Give a benefit of LANs.

Can share files

Can share hardware

What is a WAN?

Wide Area Network

Collection of LANS

Large geographical area

Hardware owned by third party telecoms companies

Give an example of a WAN.

The internet

Give 3 factors that affect network performance.

Number of users

Bandwidth available

Number of data collisions

Wired vs wireless

WIFI frequency

Type of network traffic

What are the two types of network?

Client Server and Peer-to-Peer

What is a client-server network?

All devices connected to central server, which processes requests from client computers.

It stores the user details.

Give an advantage of client-server networks.

Faster than P2P; Central backups/security

Give a disadvantage of client-server networks.

If the central device fails, the whole network fails

What is a peer-to-peer network?

All devices have equal status, there is no central server

Give 2 advantages of peer-to-peer networks.

Easy to maintain;

Cheap to setup;

If a device fails the network still runs

What is a WAP?

Stands for wireless access point. It connects a wireless device to a network.

What is a router?

A device which connects different networks together.

What are the functions of a router?

Send packets to destination;

Receives packets from internet;

Forwards packets to other computers;

Connects LAN to WAN;

Has public IP address for LAN;

Assigns private IP address to each node.

A home 'router' is a combination of what 3 devices?

Router, switch, WAP

What are the functions of a hub/switch?

Connects computers together;

Receives data packets;

Sends packets to destination nodes;

Has a routing table and their MAC address

What is the difference between a hub and a switch?

A hub is dumb - sends data to all nodes;

A switch is smart - sends data to just the node which requested it.

Out of a hub and switch, which is faster?

Switch

What is an NIC?

Stands for Network Interface Card. It connects a device to a network.

What are the 2 types of transmission media?

Wired and wireless

Define wired connection.

Uses a wire such as an Ethernet cable to connect to the network.

Give an advantage of wired connections.

Faster;

Less likely to suffer from interference(interference causes data loss+unreliability)

Longer data transmission

Give a disadvantage of wired connection.

More expensive; Less portable; Can't connect as many devices

Define wireless connection.

Uses radio waves such as Wi-Fi to connect to the network.

Give an advantage of wireless connections.

Cheaper; More portable; Can connect more devices

Give a disadvantage of wireless connections.

Slower; Suffers from interference

What is the internet?

A network of networks.

What does DNS stand for?

Domain Name System

What are the stages of the DNS?

URL sent to DNS;

DNS looks up corresponding IP address;

DNS returns IP address to browser;

If IP address not found,

elevate to higher level DNS

What does URL stand for?

Uniform Resource Locator

What is the purpose of a server?

To host websites. They are very powerful, very expensive computers.

What is a client?

A computer which connects to a server.

What is the cloud?

Remotely accessed storage accessed on the internet.

Give 3 advantages of cloud storage.

Accessible from anywhere with an internet connection

Security/backups managed by provider;

Easy to increase available storage by buying more expensive plan

Give 3 disadvantages of cloud storage.

Needs an internet connection to be accessed;

Data more easily hacked;

Issues with DPA if stored insecurely

What are the 2 network topologies?

Star and mesh

What is a star topology?

All devices connected to one central device - hub/switch/server

Give an advantage of star topology.

Fewer data collisions; Easy to add new node

Give a disadvantage of star topology.

If the central device fails the whole network fails(single point of failure )

What is a mesh topology?

All devices connected to all other devices.

Give an advantage of mesh topology.

If any of the devices fail, data can be sent down another route.

Give a disadvantage of mesh topology.

Lots of data collisions;

Lots of wires needed (expensive)

What is a virtual network?

A non-physical network. It is a private network which runs on an existing public network. Users in the virtual network can only access data on the virtual network

How is a virtual network set up?

Software used to partition from wider network

What cable is used for wired connections?

Ethernet

What is the maximum speed of an ethernet cable?

100 gigabits per second.

Ethernet is both a wire and a protocol. True/False

True - it is within the TCP/IP stack

Why is Ethernet considered a standard?

It is used many devices, to ensure wide compatibility

How does a wireless device connect to the internet?

Radio signals, usually Wi-Fi

What are the two signal bands?

2.4 GHz and 5 GHz. 2.4 can reach further but 5 is faster.

What is Bluetooth used for?

Connecting personal devices such as earphones and game controllers.

What is the range of Bluetooth?

10 metres

What is the power consumption of Bluetooth?

Low

What is encryption?

Algorithm used to scramble data into cypher text.

Encrypted data is unintelligible.

Keys are used to encrypt/decrypt data

What is an IP address?

Internet Protocol Address.

It can be changed by software.

It is used in both WANs and LANs

What is an IPV4 address?

4 decimal numbers between 0 and 255 separated by dots.

Give an example of an IPV4 address.

192.0.219.31

What is an IPV6 address?

8 hex numbers between 0 and FFFF separated by colons.

Give an example of an IPV6 address.

7FA0:FF91:2301:C50A:24E9:BA15:5301:0001

What is a MAC address?

Media Access Control Address.

It cannot be changed as it is fixed within hardware.

They are used to uniquely identify a device within a LAN.

Describe the structure of a MAC address.

6 hex numbers between 0 and FF separated by colons.

First half is the manufacturer ID, second half is the device serial.

Give an example of a MAC address.

2C:54:91:10:A5:88

Why are standards used? What are they?

Allows compatibility of hardware/software between different manufacturers.

They provide rules for areas of computing

Give 3 examples of standards.

USB; Ethernet; Wi-Fi; HDMI; MP3

What is a protocol?

Defines rules for data transmission.

What are the big 7 protocols?

TCP/IP;

HTTP & HTTPS;

FTP;

POP;

IMAP;

SMTP

What does TCP/IP stand for?

Transmission Control Protocol; Internet Protocol

What is TCP/IP used for?

Enables communication over the internet

What does TCP and IP do?

-Ensuring communication between two routers is error free.

-Ensuring data is delivered to the right device on a wide area network (WAN).

What does HTTP(S) stand for?

Hypertext Transfer Protocol (Secure)

What is HTTP(S) used for?

Websites

What does HTTP(S) do?

Defines communication between clients and servers for website viewing

What is the difference between HTTP and HTTPS?

HTTPS is secure because it is encrypted.

What does FTP stand for?

File Transfer Protocol

What is FTP used for?

Files

What does FTP do?

allows sending and receiving files between computers.

What are the 3 email protocols?

POP, IMAP, SMTP

What does POP stand for?

Post Office Protocol

What does POP do?

Is a protocol for downloading emails to a device from an email server.

-Once the email has been retrieved it is removed from the server.

What does IMAP stand for?

Internet Message Access Protocol

What does IMAP do?

-A protocol for downloading emails to a device from an email server.
-Once the email has been retrieved, a copy is retained on the mail server.

What does SMTP stand for?

Simple Mail Transfer Protocol

What does SMTP do?

Allows for communication between email sender and email server

What is a network layer?

A division of network functionality

Give 2 advantages of layers.

Self-contained;

Different developers can work on different parts;

Layer can be taken out and edited without affecting other layers;

Promotes interoperability between vendors (data exchange between hardware and software)

What are the 4 network layers?

Application, Transport, Network, Link