Networks and web technologies

Summary from the chapter in the OCR textbook :)

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  • Created by: KirstyEm
  • Created on: 19-11-20 20:40
What is the internet?
A network of networks that allow for global communication
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What is the World Wide Web?
A collection of web pages on the internet
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What is a internet service provider?
connect to backbone cables and then distribute internet connections to smaller providers.
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What is a Uniform Resource Locator?
the full address of an internet resource. Specifies the location on the internet.
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What is a internet registrar?
holds records of all existing website names that are available to be purchased. Resell domain names.
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What are internet registries?
5 global companies that have databases to hold records of all domain names currently issued.
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What is a domain name ?
the area a internet resource is in
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What is a domain name system?
A database that holds the URL against its associated IP address
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How are domain name systems used?
When a user inputs a URL, the browser requests its corresponding IP address from a local DNS. It is then passed through DNS's until the IP is found.
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What is a IP Address?
Internet Protocol address is a unique address that is assigned to a network device.
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Why are IP address used?
to indicate where packets of data is being sent from & to. So Routers can direct packets.
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What is a Wide area network(WAN)?
a network of interconnected networks (connected LANS) over a large geographical area.
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What is a Local Area Network(LAN)?
number of devices connected together by cables over a small geographical area
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Give a benefit and drawback of LAN.
Advantage: LANs can transmit data very fast

Disadvantage: it only transmits data over a short distance
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What is a Bus Topology
when all computers are connected to a single cable. It has terminators at the end of cable.
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Advantages of bus topology
Cheap to install = requires less cables = easy to add devices
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Drawbacks of bus topology
If main cable fails, no data can be transmitted

Performance drops in heavy traffic

Low security, all computers can see all the transmissions
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What is the star topology?
Network has a central node that transmits messages to the devices.
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Advantages of star topology
can isolate faults if one cable fails

consistent performance in heavy traffic

higher transmission speed than bus topology

no data collisions

easy to add new devices
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Disadvantages of star topology
costly to install (length of cable needed)

if central device goes down, all data transmission stops
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Physical VS logical topology
Physical topology- actual design layout

Logical topology- shape of pathway that data travels
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What is wifi?
Wireless technology that allows devices to connect wirelessly by using a WAP
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What is a Wireless Access Point?
usually connects to a router. A WAP gives off frequencies to transmit to stations
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What is a mesh topology?
Each node has a connection to every other node so data can be transmitted across any node.
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Advantages of mesh topology
no cabling costs

self healing - the more nodes installed=more reliable the network

new nodes automatically incorporated into the network

faster communication as there is no switch to go through
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URL Format
Method. EG) http://

Host. EG)WWW

Location EG)webpage.html

Resource EG) #element
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What is circuit switching?
Creates direct link between two devices when communicating. EG)Phone line.
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Disadvantages of circuit switching
Bandwidth is wasted during the periods where no data is sent

can only connect devices with the same transfer rate
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Advantage of Circuit Switching
as it is a direct connection so packets arrive in the same order that they were sent = simplifies reconstruction process
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Disadvantage of Circuit Switching
Easy to intercept data = security threat
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What is packet switching?
a method of communicating packets of data across a network
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What are data packets?
data that is broken into small manageable chunks. Contains a header(IPs & protocol used) and payload(actual data) and trailer(checksum).
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How do packets route across the internet?
Packets passed by different routes (router finds best route to pass onto)

fastest / least trafficked route is taken and then reassembled on the receiving end.
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What is a router?
routers are used to connect networks

Hop- going between routers

routers find the most efficient routes

share the same protocols
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What is a gateway?
a gateway can be used to translate between networks with different protocols

moves data towards their destination
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What is a media access control(MAC) address?
each NIC has a unique mac address which uniquely identifies the device
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What is a Network Interface Card(NIC)?
a NIC is needed to be able to be part of the network
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What is a Protocol?
A set of rules defining common methods of communication. Rules set a standard for all devices for them to communicate with eachover
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What is a TCP/IP protocol stack?
enables communication for computers regardless of location across the internet

set of networking protocols that work together as 4 layers connect.
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What does TCP/IP stand for?
Transmission Control Protocol/Internet Protocol
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What are the 4 layers of TCP/IP protocol stack?
1. Application
2. Transport
3. Internet
4.Link
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What is the application layer?
Uses protocols relating to the application being used to transmit data over a network
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What is the transport layer?
establish end-to-end connections with the receiving computer. Data split into packets
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What is the internet layer?
Adds IP addresses. Routers use IP address to get packets to destinations.
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What is the link layer?
a physical connection between network nodes and MAC addresses to identify NIC of computer.
MAC addresses stripped off the link layer and then packets passed back up through the layers
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What is File Transfer Protocol(FTP)?
efficient way to transfer data across networks
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What is the role of mail server in retrieving and sending emails?
POP3- responsible for retrieving emails from a mail server and stores it in upcoming emails.

IMAP- email protocol designed to keep emails on the server

SMTP-is used to transfer outgoing emails from one server to another from sender to receiver.
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What is HyperText Markup Language?
HTML is a language that webpages are written in (describes page content)
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What is Cascade Style sheets?
CSS is used that is dedicated to the style and format of the web page
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What are the tags for HTML opening and closing?
<html></html>
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What 2 tags are a normal HTML webpage split into?
<head></head>

<body></body>
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What is the HTML tag for titles and headings?
<title></title>


<h1></h1> ect
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What is the HTML tag for a new paragraph?
<p>
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What is the HTML tag for images?
<img src= >
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What is the HTML tag for hyperlinks?
<a href="">Linkkk</a>
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What is the HTML tag for numbered lists?
<ol>
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What is the HTML tag for bullet point lists
<ul>
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What is the HTML tag for each item in a list
<li>
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What is the HTML tag for dividing a page into separate areas?
<div></div>
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What is embedded/internal/inline CSS?
CSS script is added directly into the HTML document with style tags for one off adjustments
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What us External CSS?
When a link to an external CSS sheet is added to a HTML code.
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How would you add an external css sheet?
<link href="style.css" rel="stylesheet" type="text/css">
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How is an identifier used?
uses a # before an ID name
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How are classes used?
uses a . as a prefix to a class name
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how would you write a CSS in an external sheet?
.body{

margin:"";
padding:"";
font-family:"";
text-align:"";
background-color:"";

}
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What does a web form do?
enables a website to collect user input data
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Layout an example of a HTML form code
<form action="process.php" action="post">
<label>enter name</label>
<input type="text" id="name" value=""/>
<button type="submit">enter</submit>
</form>
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What does a HTML submit button do
Sends data to a form handler in the attribute specified in the form tag
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What is JavaScript?
a script language that adds interactivity to webpages.
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What translator does Javascript use?
Interpreter
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What tags is JavaScript code in?
<script></script>
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how do you write directly into a webpage document with JavaScript?
document.write("");
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How do you display an alert box on JavaScript?
alert('')
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How are functions declared in JavaScript?
{}
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How are validation functions done on javascript?
validateForm()
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What is client server networking?
when one or more computer(client) is connected to a powerful central computer

each client holds its own resources

clients can also accsess resources held by server

in large networks each client can hold different tasks
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Advantages of client server networking
security = all files stored centrally = assess to rights managed by server

backups centrally

data can be shared
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Disadvantages of client server networking
Expensive to install

IT staff needed to maintain and run network
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What is cloud computing?
provides accsess to files via the intenet

uses a client server model

Eg. OneDrive
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What is peer to peer networks?
no central server, each computer is connected to each over on a network. Can share files
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Advantages of peer to peer networks
cheap to set up

can share resources

easy to maintain
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Disadvantages of peer to peer networks
used for online piracy

impossible to trace files

implications in movie industries(lower money to reinvent into new movies)
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Other cards in this set

Card 2

Front

What is the World Wide Web?

Back

A collection of web pages on the internet

Card 3

Front

What is a internet service provider?

Back

Preview of the front of card 3

Card 4

Front

What is a Uniform Resource Locator?

Back

Preview of the front of card 4

Card 5

Front

What is a internet registrar?

Back

Preview of the front of card 5
View more cards

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