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48 Cards in this Set

  • Front
  • Back
Computer network that spans a relatively small area.

Uses proprietary cabling owned by the company e.g. schools

Computer network that extends over a large geographical distance.

Uses third party cabling to transfer data between terminals across the network. E.g. Internet

Domain Name Server.

Uses a database of website addresses and their IP addresses to allow a user to access websites.

DNS steps
1) a website address (domain name) that is entered is looked up in a DNS database to find the matching IP address

2) if it can’t find the address, it searches on other DNS servers

3) Once found the IP address of the website is accessed to retrieve the data

4) This data is then sent back to the user who can then view the website

DNS advantages
1) A website address is easier to remember than an IP address

2)a connection to one DNS server means that you can access all addresses on all DNS servers

3)The upgrade from IPv4 to IPv6 is managed centrally

Packet Switching
Data transmission in which a message is broken into a number of parts which are sent separately
Over whatever route is most efficient for each packet, and reassembled at the destination
Packet Switching steps
1) The website data is broken down into small packets/chunks of data

2) Each packet is numbered; given the sender’s and recipient’s IP address

3)Sent separately

4)Packets are reassembled at the destination; and checked for errors

5)lost or corrupted packets are resent

Protocol layers advantages

Can be edited withoutaffecting other layers

Developers can concentrate on one network area without knock-on effects

Mesh Network

Nodes act as routers for data in order to relay and spread data in the network

Mesh Advantages

Self-healing/have no single point of failure

Data canbe transmitted from different devices simultaneously

Require no additionalhardware.

Mesh Disadvantages

Can be expensive to install/often haveredundant connections

network maintenance and administration is morecomplicated than with a star network.


A set of rules

Physicaltransmission media

Copper cable

Twisted pair

Cat 5/Cat 6 cable

Fibre Optic

Virtual Network

Network does not consist of a physical (wired or wireless) connection between two computing devices


Passes data packets across a network towards their final destination


Smart multi-plug adaptor only sends packets to the intended recipient, using its MAC address

Reduces network traffic and increases transmission speed


Central, multi-plug adaptor that when a packet of data is received, it broadcasts the packet to all devices on the network


The encoding of data so that it can nolonger be understood

Encryption importance

To avoid personal data being stolen - especially in virtual networks where computers may use the same physical cabling

encryption will preventany data from one network from being understood by users of another


The amount of data that can be transferredat one time


The speed that data travels during transfer(or delay in receiving)

Error rate

The number of collisions in high networktraffic.sources

Retransmission rate

How promptly corrupted or lost packets can be resent

Network performance factors



Error rate

Retransmission rate


Network Interface card

Component that allows connection of a computer to a computer network

MAC Address

Unique identifier assigned to network device

Provides a unique MAC address to which tosend data packets

Wifi signal factors

Walls, other devices, neighbours networks using overlapping channels

Download entire messages to your local device and delete them from the server
Only download the message header until the message is opened and will leave the message on the server

Synchronises all devices with the server’s mailbox server

SMTP (Simple Mail Transfer Protocol)
Transferring email between remote email servers
TCP (Transmission Control Protocol)
Breaks up and reassembles messages sent over the Internet into small chunks called packets. Detects errors and Resends lost messages
IP protocol
Routes the individual packets
TCP/IP protocol stack
Defines four layers in which different protocols operate to pass data packets across a network
HTTP(hypertext transfer protocol)
Accessing and receiving web pages in the form of HTML
HTTPS (secure protocol)
Encrypts the information so that it cannot be understood if it is hacked
FTP (File Transfer Protocol)
Sending or retrieving files to or from a remote server or computers data packets across a network

Email steps

Email is written and sent to a local mailserver

The mail server forwards this onto the other persons mail server via the Internet

Other user logs into their email account and downloads the message from his localmail server

The Cloud
Resources, data and information hosted on remote servers
Software as a Service
Cloud-based servers enable access to software on demand e.g. Office software
Cloud Computing advantage
No need to have the software installed on a local machine. No need for a big, powerful computer.

Can access the software (and your data) from any Internet-connected computer.

Backing up data is no longer crucial – it is done by the service provider

Cloud Computing disadvantage
Idea of handing over important data to another company worries some people

Sensitive data could be more vulnerable to hacking

Usually only a small amount of data storage is free

Powerful computer which provides services or resources required by any of the clients
Computer which requests the services or resources provided by the server
Role of the client
The client sends requests to the server, Waits for a reply, Receives the reply
Role of the server
Waits for requests from a client, Acknowledges the request, the requested data is sent back to the client
Client-server advantage
All data can be backed up centrally rather than on each individual computer. Security is better because data is held in one location rather than all over the organisation. Users can log in from any computer on the network and access their data
Client-server disadvantage
If server goes down, no access to files. Can require specialist IT staff to administer the network

Internet host services

Website hosting

Online file hosting

Video hostingservices