Yr 11 - AQA GCSE Computer Science-Computer networks revision

Yr 11 - AQA GCSE Computer Science-Computer networks revision

Computer networks

Computers and other technological/electronic devices can be connected together in a number of different ways.

Depending on the device and the range of communications, we can classify the networks as PAN, LAN or WAN.

What respective areas/how large areas do each of these networks cover?

Multiple Choice

One of the network systems which can be created is a PAN. What communications protocol/method does a PAN use?

• Bluetooth

• WiFi

• Radio

• Ethernet

Physical wired networks

Wired networks can be connected via different wiring systems.

Wired networks can be cabled using copper cables or fibre-optics.

What are the respective advantages/disadvantages of these different cabling systems?

Multiple Select

When setting up cabled networks - they can be constructed as which TWO different network topologies?

• Ethernet

• Bus

• Star

• LAN

Communications protocols

For devices on any communications networking system - the information flowing along the network will be using different communications protocols (depending on the data/information being communicated).

Communications protocols... a system of rules that allow two systems to exchange information.

Typical communications protocols include: TCP, UDP, HTTP, HTTPS, FTP, SMTP and IMAP

Multiple Select

Which TWO of the communications protocols are used in e-mail communications and exchanges?

• IMAP

• SMTP

• FTP

• HTTP

Network security

There are multiple ways of keeping networks secure - preventing unauthorised users from making use of your network, or preventing unauthorised people from 'reading' the data being sent across your network.

What is the term given to making information 'unreadable' by unauthorised users, even if they 'intercept' the data packets?

Multiple Choice

For any device attached to a network, which communicates and sends/receives data across the network - it has TWO unique numbers associated with it.

What is the name, or term given to the number on the TOP of this image - 9C-35-5B-5F4C-D7 - which uniquely identifies this hardware?

• domain name

• Ethernet address

• IP address

• MAC address

Networking with TCP/IP

For all devices on a TCP/IP network - when the client sends the data to another system or device, the data must go through a number of levels.

These levels are part of the 4-layer TCP/IP model.

Application - software applications sit at this level

Transport - sets up/creates the data packets

Internet - addresses the packets

Link/Network - manages the packets through the network cards

Multiple Choice

Which layer of the 4-layer TCP/IP model would an e-mail program, or web browser be at/sit?

• application

• transport

• internet

• network/link

Data packets

All network/Internet communications splits data into packets.

Each data packet is made up of a number of different parts.

Multiple Select

As computers send data to another computer - the receiver's IP address is included on the packet. Why does a packet need to include the sender's IP address?

• To know where the packet came from

• To be able to ask for the packet to be sent again in case of packet corruption

• To ensure both computer systems are compatible

• To be able to scan for viruses

PANs, LANs, WANs and connections

It is possible to connect devices in PANs, LANs and WANs in a number of different ways, using a range of different communication protocols, and using a range of different hardware.

How does the hardware and communications protocol(s) differ in these three different types of network?

Multiple Choice

Wired networks can use fibre-optic cables... or copper cables. Which one of these is less likely to suffer from interference (from electromagnetic interference), can be used to communicate over very long distances but costs more money?

• Copper cable

• Fibre-optic cable

Poll

Data sent from one device (over a network) to another device... is split up into packets ... sent using TCP or UDP protocols

Some data is 'more important' than others - all the data packets (for some applications) must arrive uncorrupted!

BUT sometimes we prefer 'speed' over accuracy... which one of these communications protocols might be best suited for online gaming?

Networks and security

For any computer system/device attached to a network - there is a potential risk/threat to that system or device.

There are a number of ways of protecting those network-attached devices, including (but not limited to):

- firewalls - will 'reject' any suspicious data packets, stop any blacklisted IP address attacks

- MAC address filtering - accept only white-listed MAC addresses

- authentication

- encryption

Multiple Select

Which of the following could be considered as suitable authentication methods to ensure only permitted users can access computer networks using their devices?

The end!