Local Area Networks (LANs), Wide Area Networks (WANs) Wires, Wi-Fi and Protocols

What is a network?

Two or more computers connected together to share information and resources

What is a LAN?

A Local Area Network confined to a small geographical area

What is a node in a network?

Each device connected to the network

What are advantages of LANs?

They enable communication, sharing of information and devices, centralized updates, and distributed processing

What are disadvantages of setting up a network?

They require expertise to install and maintain and can have security issues

What is bandwidth?

The carrying capacity of the network data transfer media

Which type of cable offers more bandwidth, copper or fibre optic?

Fibre optic

What happens when too many users use a network at the same time and what is the solution?

More traffic so more bandwidth is needed

What can cause network interference?

Certain electronic devices

What must each node in a LAN contain?

A Network Interface Card

What does a Network Interface Card do?

It converts data signals to be transferred across the network and defines how a computer connects to a network

What is needed for a wireless network?

A wireless access point

What is an advantage of wireless networks?

No building work is needed and new nodes can be added easily

What may be required for a wired network?

A hub or a switch

What is a hub?

A device that connects nodes together, making them act as a single segment

What is a switch?

An intelligent hub that sends data only to the required node

What is a router used for?

To connect a LAN to the Internet and manage data packets between networks

What is a peer-to-peer network?

A network where all computers have the same status and share resources equally

What is a disadvantage of peer-to-peer networks?

Data transfer can be slow due to collisions and shared processing and easy virus spread

What is a client-server network?

A network where one computer (the server) provides services to others (clients)

What does a server do?

Offers services and data, manages traffic, and logs client activity

What is a network topology?

The layout or setup of a LAN

Describe a bus topology with its adv and dis

One cable connects all nodes; cheap but slow and vulnerable to wire faults

Describe a ring topology with its adv and dis

Nodes are connected in a circle; data travels one way; fewer collisions but the whole network fails if the cable breaks

Describe a mesh topology with its adv and dis

All devices are connected to each other; multiple data routes but expensive

Describe a star topology with its adv and dis

All nodes connect to a hub or switch; fast and reliable but costly due to many cables and hardware

What is a WAN?

A Wide Area Network that covers a large geographical area, possibly worldwide

What is the Internet?

A massive network of networks

What is the World Wide Web (WWW)?

A collection of websites for sharing information

What is a host?

A computer that serves clients over the Internet

What is web hosting?

When a company stores websites on servers

What is an IP address?

A unique number assigned to a device on the Internet to locate it

What does ISP stand for?

Internet Service Provider

What is a URL?

A Uniform Resource Locator; it's a web address

What is the Domain Name System (DNS)?

A system that matches URLs to IP addresses

What happens when you search a URL?

The ISP finds the IP address of the website and connects you to it

What is ‘The Cloud’?

A network of servers on the Internet used for storing and accessing data

List 3 advantages of cloud computing

Unlimited data, accessible from any device, data can be backed up

What is a drawback of cloud computing?

Sensitive data might be stored in countries with different data laws

What are the two main types of cable used to transport data between computers using ethernet?

Twisted pair copper cables and fibre optic cables

What are ethernet cables made of?

Twisted pairs of copper wires

How is data transported in twisted pair cables?

Via electrical signals

Why can twisted pair cables suffer from interference?

Because closer wires disrupt electrical signals

What are fibre optic cables made of?

Glass fibres

How is data transported in fibre optic cables?

Via light signals

Why don’t fibre optic cables suffer from interference?

Because they use light instead of electricity

How fast can data travel through fibre optic cables?

At a fraction of the speed of light

What is a disadvantage of fibre optic cables?

They are expensive

What does Wi-Fi allow access to?

wireless LANs to connect to each other

How does Wi-Fi send data?

Using radio waves

What is Wi-Fi classified as?

A standard

What is a standard in computing?

A set of rules for communication

What frequency bands do computers use to send and receive data?

0 - 6 GHz

Why are frequency bands split into channels and how?

To send more data with less interference by covering smaller frequency ranges

What is the purpose of sub-bands in data transmission?

To prevent interference by slightly switching frequencies

How many devices can Bluetooth support at once?

A small number

What is Bluetooth's range compared to Wi-Fi?

Shorter

How close do Bluetooth devices need to be?

Close together

What is encryption?

Scrambling data before sending it over a network

What does an encryption key do?

It alters data to convert cipher text into plain text

How are files sent over the internet?

They are split into millions of data packets

How do packets travel across the internet?

By different routes according to availability

What happens to packets at the end of their journey?

They are reassembled

What information does a data packet contain?

Error check, sequence number, return address, destination address

What is an error check in a data packet?

A system with a calculation to detect corruption

What does it mean if the error check number matches?

The data hasn’t been corrupted

What is the sequence number in a packet for?

To reassemble the packets in the correct order

What is the return address in a data packet?

The address of where the data was sent from

Why is a return address important?

So data can be resent if it is corrupt

What is the destination address in a data packet?

Where the data is being sent to

What does every network card have?

A MAC address

What is a MAC address and what is it made of?

A unique, unchangeable, 12-digit hexadecimal number for a device

What is the purpose of a MAC address?

To find a device’s destination on a network

What do TCP and IP stand for?

Transmission control protocol and Internet protocol

What does TCP do?

Ensures data is split, sent, and reassembled the same way

What does IP do?

Ensures data is sent in the most efficient way

What is packet switching?

A way to send data efficiently over the internet

How does packet switching work?

It splits data into packets and sends them via different routes

Why might packets be sent to different routers?

To avoid traffic and ensure efficiency

What happens to packets at the destination?

They are reassembled

What does HTTP stand for?

Hyper Text Transfer Protocol

What does HTTP govern?

The way websites and web servers are accessed

What does HTTPS stand for?

Hyper Text Transfer Protocol Secure

What is the difference between HTTP and HTTPS?

HTTPS ensures all data is encrypted

What does FTP stand for?

File Transfer Protocol

What does FTP do?

Ensures all clients can access files from a server in the same way

What does POP stand for?

Post Office Protocol

What does POP govern?

How emails are accessed from a server

What does IMAP stand for?

Internet Message Access Protocol

How is IMAP different from POP?

Email remains on the server and syncs across devices

What does SMTP stand for?

Simple Mail Transfer Protocol

What does SMTP govern?

How data is sent between mail servers

What is Layer 1 of the internet?

Data link layer and physical layer

What does Layer 1 do?

Provides the physical transport of data through electrical signals

What is Layer 2 of the internet called?

Network layer

What does Layer 2 do?

Provides the routing of data across the network

What is Layer 3 of the internet?

Transport layer

What does Layer 3 do?

Provides transport of data between devices by splitting files into data packets

What is Layer 4 of the internet?

Application layer

What does Layer 4 do?

Provides user access to applications, websites, files, email