Unit 5 - Networks

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What is a network?
A network is a series of computers and other devices that are connected together and can share data and resources.
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What is the difference between the internet and the world wide web?
The internet is an international network of computers (a network of networks) whereas the world wide web is one use we get from that network.
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Describe WAN.
A Wide Area Network (WAN) is any network in which computers communicate across a wide geographical area, using resources supplied by a 'third party carrier' such as British Telecoms.
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Describe ways of how a WAN can connect?
A WAN uses cables, telephones, lines, satellites and radio waves to connect.
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Describe LAN.
A Local Area Network (LAN) is any network that communicates covering a small geographical area.
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How does the sending computer organise packets?
Each packet of data contains the same number of bytes. Also packets are marked with the packet number and the total number of packets in the transmission.
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What happens when the recipient computer receives the packets?
The recipient computer re-orders the packets into the correct order. Each packet is checked for errors, any corrupt packets are requested to be resent.
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What happens when packets are lost?
The recipient computer will acknowledge receipt of packets. Any packets not acknowledged after a set time interval will be automatically resent by the sending computer.
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Explain the role of a router.
Each node is a crossroads and so the router directs data packets to their destination along a path which is least busy at that moment.
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What does ISP stand for? Give an example.
Internet Service Provider. An example is BT Broadband.
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What does IP stand for?
IP stands for Internet Protocol Address.
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What does URL stand for?
URL stands for Uniform Resource Locate.
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Describe Domain Name System.
DNS technology allows you to type a name such as www.google.co.uk into your web browser. It the translates the web address into an IP address.
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Explain the Internet Protocol.
Every computer and other device connected to the internet has an IP address. Packets are labelled with the sender's address and the destination IP address.
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What is the purpose of Media Access Control (MAC)?
A MAC address is assigned to each Network Interface Card (NIC) by the manufacturer. Your computer may have more than one MAC address.
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Name two advantages of MAC addresses.
MAC addresses allow you to filter devices and allow you to identify a device.
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Describe Network Interface Cards (NIC).
They can we wired or wireless. They are built into every networked device.
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What is a switch?
A smart multi-plug adaptor that only send packets to their intended recipient using their destination MAC address.
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What is a WAP?
A Wireless Access Point allows wireless devices to connect to a wired network using Wi-Fi.
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What is a PAN?
A Personal Area Network is centered around a single user. Bluetooth is used to connect devices and devices can be tethered.
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What is bandwidth?
Bandwidth is the amount of data that can be carried at a time.
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What is connection speed measured in?
Measured in Mbps (Megabits per Second)
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Name some factors that affect network performance.
Bandwidth, connection speed, latency and errors/collisions in network traffic.
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What is latency?
Latency is the time of delay of transmitted data travelling from the sender to the recipient.
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Describe Ethernet Protocols.
'Ethernet' refers to a family of standard local networking 'protocols' or rules. Decides what format to transmit the data.
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Draw the Star Topology.
Star Topology:
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Give advantages of the Star Topology.
There is a faster data transfer as fewer data collisions, the data goes from switch to workstation. If one cable fails the others aren't affected.
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Give disadvantages of the Star Topology.
The Star Topology requires additional hardware e.g. switch. If the central device fails the whole network fails.
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Draw the Bus Topology.
Bus Topology:
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Give two advantages of the Bus Topology.
Less cable is needed making it cheaper and is easy to install.
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Give two disadvantages of the Bus Topology.
There are more collisions as there are lots of machines on the network. The topology fails if the main cable is damaged or fails. There is also a security risk.
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What is Authentication?
Authentication is checking that the computer and the user are allowed to access content. This is most commonly done using a username and password.
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Describe Intercepting data.
Data is transmitted over a network can be intercepted.
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What is encryption?
Encryption is changing the format of data so that it can no longer be easily understood.
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What is a Private Key?
Symmetric encryption. A single key is used to encrypt and decrypt a message and must be given to the recipient of your message to decrypt the data.
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What is a Public Key?
Asymmetric encryption. Two keys are used - one to encrypt and the other to decrypt. This is more secure as it means that you never have to send or reveal your decryption key.
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What is a Firewall?
A Firewall acts as a protective screen. It allows outgoing traffic but checks incoming traffic. It can filter unwanted inbound traffic.
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Describe Wireless Encryption Standards.
The most common wireless security standards are Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA).
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What is a protocol?
A protocol is a set of rules.
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Whats is the HTTP protocol?
The Hypertext Transfer Protocol (HTTP) is used for accessing and receiving web pages in the form of HTML file on the Internet. The protocol requests the web server to upload the requested web page to the user's browser for viewing.
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What is the HTTPS protocol?
The Hypertext Transfer Protocol Secure (HTTPS) encrypts the information so that it can't be hacked.
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What is the FTP?
The File Transfer Protocol (FTP) is used for sending and receiving files to or from a remote server or computer.
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What is the SMTP?
The Simple Mail Transfer Protocol (SMTP) is an email protocol used for transferring emails between remote email servers.
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What do the POP and IMAP protocols do?
These email retrieval protocols fetch message data and attachments from your remote mail server.
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Describe POP.
POP will download entire messages to your local device and delete them from the server.
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Describe IMAP.
IMAP will only download the message header until the message is opened and will leave the message on the server.
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What is the TCP protocol?
The Transmission Control Protocol (TCP) breaks up messages sent over the Internet into small chunks called packets. The packets are then reassembled at the other end. The errors are detected and and resends lost messages.
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What is the IP protocol?
The Internet Protocol routes the individual packets.
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Describe the Application Layer.
The application selects the correct protocol to use depending on which application it is and what you are trying to do.
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Describe the Transport Layer.
The Transport layer creates the connection between two computers or 'hosts'. The two computers agree the communication settings and the size of what they will send and receive.
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Describe the Network Layer
Routers operate on the Network Layer. Destination addresses are written onto the packets ready for transmission. The packets are then sent.
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What is the Link Layer?
The Link Layer is the physical hardware that connects the two hosts such as the NIC and the cabling. OS device drivers also operate on this layer.
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Give two advantages of layers.
The layers are self contained. Also different hardware or software operates on a particular layer providing interoperability between providers and systems.
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What does UDP stand for?
User Design Program.
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Describe UDP.
The UDP maintains an open connection to send a stream of packets without checking they're received correctly. It's most useful where it doesn't need to make sense to wait and fill in any gaps lest by lost packets such as online gaming.
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Other cards in this set

Card 2

Front

What is the difference between the internet and the world wide web?

Back

The internet is an international network of computers (a network of networks) whereas the world wide web is one use we get from that network.

Card 3

Front

Describe WAN.

Back

Preview of the front of card 3

Card 4

Front

Describe ways of how a WAN can connect?

Back

Preview of the front of card 4

Card 5

Front

Describe LAN.

Back

Preview of the front of card 5
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