Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
48 Cards in this Set
- Front
- Back
LAN
|
Computer network that spans a relatively small area.
Uses proprietary cabling owned by the company e.g. schools |
|
WAN
|
Computer network that extends over a large geographical distance.
Uses third party cabling to transfer data between terminals across the network. E.g. Internet |
|
DNS
|
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. |
|
Protocol |
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 |
|
Router |
Passes data packets across a network towards their final destination |
|
Switch |
Smart multi-plug adaptor only sends packets to the intended recipient, using its MAC address Reduces network traffic and increases transmission speed |
|
Hub |
Central, multi-plug adaptor that when a packet of data is received, it broadcasts the packet to all devices on the network |
|
Encryption |
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 |
|
Bandwidth |
The amount of data that can be transferredat one time |
|
Latency |
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 |
Bandwidth Latency Error rate Retransmission rate |
|
NIC |
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 |
|
POP
|
Download entire messages to your local device and delete them from the server
|
|
IMAP
|
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 |
|
Server
|
Powerful computer which provides services or resources required by any of the clients
|
|
Client
|
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 |