Year 10 Networks - Gcse Computer Science

Front 1

LAN

Back 1

Computer network that spans a relatively small area.

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

Front 2

WAN

Back 2

Computer network that extends over a large geographical distance.

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

Front 3

DNS

Back 3

Domain Name Server.

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

Front 4

DNS steps

Back 4

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

Front 5

DNS advantages

Back 5

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

Front 6

Packet Switching

Back 6

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

Front 7

Packet Switching steps

Back 7

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

Front 8

Protocol layers advantages

Back 8

Can be edited withoutaffecting other layers

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

Front 9

Mesh Network

Back 9

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

Front 10

Mesh Advantages

Back 10

Self-healing/have no single point of failure

Data canbe transmitted from different devices simultaneously

Require no additionalhardware.

Front 11

Mesh Disadvantages

Back 11

Can be expensive to install/often haveredundant connections

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

Front 12

Protocol

Back 12

A set of rules

Front 13

Physicaltransmission media

Back 13

Copper cable

Twisted pair

Cat 5/Cat 6 cable

Fibre Optic

Front 14

Virtual Network

Back 14

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

Front 15

Router

Back 15

Passes data packets across a network towards their final destination

Front 16

Switch

Back 16

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

Reduces network traffic and increases transmission speed

Front 17

Hub

Back 17

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

Front 18

Encryption

Back 18

The encoding of data so that it can nolonger be understood

Front 19

Encryption importance

Back 19

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

Front 20

Bandwidth

Back 20

The amount of data that can be transferredat one time

Front 21

Latency

Back 21

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

Front 22

Error rate

Back 22

The number of collisions in high networktraffic.sources

Front 23

Retransmission rate

Back 23

How promptly corrupted or lost packets can be resent

Front 24

Network performance factors

Back 24

Bandwidth

Latency

Error rate

Retransmission rate

Front 25

NIC

Back 25

Network Interface card

Component that allows connection of a computer to a computer network

Front 26

MAC Address

Back 26

Unique identifier assigned to network device

Provides a unique MAC address to which tosend data packets

Front 27

Wifi signal factors

Back 27

Walls, other devices, neighbours networks using overlapping channels

Front 28

POP

Back 28

Download entire messages to your local device and delete them from the server

Front 29

IMAP

Back 29

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

Front 30

SMTP (Simple Mail Transfer Protocol)

Back 30

Transferring email between remote email servers

Front 31

TCP (Transmission Control Protocol)

Back 31

Breaks up and reassembles messages sent over the Internet into small chunks called packets. Detects errors and Resends lost messages

Front 32

IP protocol

Back 32

Routes the individual packets

Front 33

TCP/IP protocol stack

Back 33

Defines four layers in which different protocols operate to pass data packets across a network

Front 34

HTTP(hypertext transfer protocol)

Back 34

Accessing and receiving web pages in the form of HTML

Front 35

HTTPS (secure protocol)

Back 35

Encrypts the information so that it cannot be understood if it is hacked

Front 36

FTP (File Transfer Protocol)

Back 36

Sending or retrieving files to or from a remote server or computers data packets across a network

Front 37

Email steps

Back 37

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

Front 38

The Cloud

Back 38

Resources, data and information hosted on remote servers

Front 39

Software as a Service

Back 39

Cloud-based servers enable access to software on demand e.g. Office software

Front 40

Cloud Computing advantage

Back 40

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

Front 41

Cloud Computing disadvantage

Back 41

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

Front 42

Server

Back 42

Powerful computer which provides services or resources required by any of the clients

Front 43

Client

Back 43

Computer which requests the services or resources provided by the server

Front 44

Role of the client

Back 44

The client sends requests to the server, Waits for a reply, Receives the reply

Front 45

Role of the server

Back 45

Waits for requests from a client, Acknowledges the request, the requested data is sent back to the client

Front 46

Client-server advantage

Back 46

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

Front 47

Client-server disadvantage

Back 47

If server goes down, no access to files. Can require specialist IT staff to administer the network

Front 48

Internet host services

Back 48

Website hosting

Online file hosting

Video hostingservices