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Learning Aim B

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1ClientThe computer you use to access the internet is a client. You are provide services from your ISP. Its a computer/device that uses services provided by a server.
2RouterDevices that route (direct) data (in small packets) traffic through a network.
They are intelligent because they will try to find the best route.
3PoPPoint of Presence is an access point to the internet. An ISP may have several PoP to allow good access to the internet.
4NAPNetwork Access Points. Where different networks interconnect such as your home network onto the internet.
5BackboneA big cable(often fiber optic or copper) that's connects a large number of devices in the core of the internet
6ISPInternet Service Provider. A company such as Sky. It allows connection to the internet. It would be too expensive to access the internet so ISPs make it easier for you to do so.
ISPs can give additional services for a fee such as tech support.
Access to WWW
Allows web hosting
7ServerRun special servers to serve other computers. Different types include files. print, web and email servers
8InternetThe internet is a global network of interconnected computers that allows packets of data to be exchanged between computes and devices.
9Network Diagram
10Network Diagram Stages of connecting to internet
11Advantages: Dial Up Connections (Wired Connections via modem and phone wires)Can use existing telephone wires
Gives connection where broadband is not available
12Disadvantages: Dial UpOlder technology can give poor reception
Usually slower than other methods
Conversion between digital and analog can cause errors and cut you off
13Advantages: Broadband (with connection/Ethernet)Better reception and speed than dial Up
Usually very fast speeds with connection
You can still use your telephone and internet connection
14Disadvantages: Broadband (with connection)Wired, so has to be used on a stationary computer
Broadband not available in many rural areas
15Advantages: WirelessNot fixed to a stationary computer
Can be used wherever wireless Internet is available (e.g Wi-Fi hotspot)
16Disadvantages: WirelessNeeds to have wireless internet available
Can be less secure than wired
Tends to be slower than wired
17BandwidthHow we measure the speed of an internet connection. It is how much space there is that can carry digital data.
Having high bandwidth means more faster times. This means more data can be moved
18Bandwidth
19ProtocolsProtocols are rules that allow computer systems to connect with different systems to transfer data
20IPInternet Protocol
Is responsible for handling the routing of packets -
Thats addressing, sending and receiving packets over the Net
21HTTPHypertext Transfer Protocol
Set of rules that handles what we do on the web
It handles your request to load a page from the web server
It also handle the response to download the web file and all its files on your computer
22Secure HTTPSThis is HTTP but is secure.
This means the data is scrambled before sending across the internet So if the data is intercepted, it cant be understood
This protects privacy from hackers
23FTPFile Transfer Protocol
Protocol which allows files to be transferred between two devices. It is usually to upload or download files to a server.
It is often used by web developers to transfer files from the serer to their web page.
It is an old protocol invented before the web.
To use it you usually need a username and password
24TCPTransmission Control Protocol
Is responsible for Breaking data packets and assembling them again when they arrive (to the client)
25When hyperlink is clicked
26BrowsersWeb pages are accessed through browsers
These applications which allow a user to enter a URL and view a webpage
Your browsers reads HTML code and displays the page
27HyperlinksThe Web works because of hyperlinks
They connect web pages together
When a hyperlink is clicked, a user is taken to another page on site, or taken to another website.
28Web serversWebsites are stored on web servers
When you access a webpage, the page is temporarily downloaded to your computer
Its the web servers job to deliver the web page requested
29URLs Uniform Resource Locator
30ProtocolTells the browser what to do with the URL
31DomainThe name of the website
U have to pay for it and if its already taken you cant do anything about it
32PathThis points to the specific webpage
33Search Engines - How it works
34Client SideYour device that you use to make a request on a search engine
35Search EngineSpecial websites that allows users to find data on the internet.
Users enter keywords in the search engine and it will find the most relevant results
Examples include Google
36Server SideThis is where the web servers and databases are which works on finding the data and web pages you need
37Spider/ Web crawlersThese bots look for new or updated pages and log them in the search engines database called the Index
38IndexThis is a database of web pages
wen crawlers find new web pages and stores them in the index
39DatabaseWorks with the web servers.
The index is a database of web pages
40Sponsored Links resultsPeople that pay for sponsored links will have their websites on the top result.
41PopularityAfter the sponsored links, the websites that are most relevant and most popular would come on top on the search results
42AdvertsAdverts are relevant in google searches and would often be place on the side or stop of the results page
43Store and ForwardEmails are stored on servers and then forwarded to the receiver.
Emails are sent from a users outbox then received in the recipients box
The two user do not have to be online for the email to be sent
44Address book/Contact groupStore contacts and you can use distribution to send emails to a lot of people simultaneously
45CCCarbon Copy
This means you can send other people a copy of the email so they can see
They can also see other recipients addresses
46BCCBlind Carbon Copy
This is where you are able to send a copy to other people while hiding their address so others cant see
47Benefits of E-mailAttachments: You are able to attach files such as images or dos to your email
Speed of delivery: Emails sends in seconds
Contacts: You are able to send one email to multiple people and send CC or BCC to people
Webmail: You can access email anywhere if you have a internet access
48Drawbacks of E-mailSpam: You can get lots of spam emails which can contain viruses
Viruses: Attachments can contain code which can harm your computer
Phishing: Fake emails designed to trick people to give personal info
No Access: If you do not have an internet access you cant use email and if the recipient does not have internet access they can access the email
Late replies: You cant expect an instant response
49Email Protocols Email Component: Username
50SMTPSimple Mail Transfer Protocol
This pushes email to a server
If it doesn't work at first it will keep trying till its sent
51IMAPInternet Message Access Protocol
Let you access your email on a server
When logging in, your email gets pulled from the server
So you can access it anytime anywhere with an internet connection
Stores a copy on the servers
Store and Foward
52POP 3Post Office Protocol 3
Originally came before web mail when people used email client software e.g MS Outlook
You downloaded emails from the server
You are able to delete the emails from the server
53Web mail+ All your messages stay on a server
+ Can access email on many devices
+ Email backed up
- You must have net connection
- Can be slow service
- limited files sending
- Spam emails and risk of viruses
Not knowing if you receive your email
54Email client+ Email downloaded to client machine
+ Can access them, even not online
+ Client software has more features
- Emails lost if computer crashes
55Data exchanged Data Packet Diagram
56Packet SwitchingIs a process of data bring broken into packets being sent through a network and then reassemble at the other end
57Advantages of packet switchingPackets chose different routs so the flow is efficient
Big files can still be sent but don't clog network
Packets give security benefits because intercepted, the hacker will only have one part of the file
58Disadvantages of packet switchingIf one or more packets are lost or corrupted during transmission , the whole file will not be received correctly
59CodecsSpecial computer program which speeds up the transmission of the audio and video data by encoding and decoding the packets
Data is converted from analog to digital
60Transmission ModesWays devices on a network communicate and transmit data
61SimplexSignals go in one direction only. Data cannot be send back to it.
e.g A remote to the TV
62Half DuplexData signals can be sent both ways but not simultaneously / not in the same time. They take turns to signal. e.g walkies talkies
63Duplex / Full DuplexSignals are transmitted and sent both ways at the same time. e.g Phone to Phone
64Serial TransmissionData Transfer: Bits of data (8 bits) are transferred one at a time over a wire .
Benefits: Good over large distances
Drawbacks: Data have to be broken into individually bits
65Parallel TransmissionBits of data are transmitted simultaneously which means a whole byte (8 bits) can be sent at the same time
Benefits: Faster than serial because more bits are transferred per second
Drawbacks; Only for shorter distances e.g less than 5 meters
66UTPUnshielded Twisted Pair
Contains copper wires that are twisted together
Used for LANs
67STPShielded twisted pair
Same as UTP but with a foil like wrapper around it, giving it protection
68Advantages of UTP/STPCheaper than other methods
Reliable
STP cable has a protective layer to protect data signals from interference
69Disadvantages of UTPCan cause interference
Less reliable than STP
70Co-axialSolid thick copper wire with thick shielding
Used to connect TV with aerial
Advantages: Reliable
Disadvantages: Slow, Low capacity, used for short distances
Inflexible and can make noise
71Fibre opticStrands of glass carry data as light. Used for backbone of network
Advantages: Very fast
Little interference and Used for long distances
Disadvantages: Expensive
72Wireless transmission MethodsData is transmitted wireless using different types of waves from the electromagnetic spectrum
73InfraredUses infrared lights to transmit data which is a very high frequency light
Uses: A remote to a TV
Advantages: Reliable
Disadvantages: Short range
Devices must be in line of sight
Can suffer from interference
74Bluetooth MicrowaveUses wavelengths to transmit data
Use: Can connect things like a wireless mouse to a computer
Advantages: Good for medium distances
Don't need line of sight to work
Disadvantages: Can suffer from other devices
75SatelliteUses satellite in space to relay data between points on earth e.g GPS /
Uses: Sat Nav, Weather
Advantages: Good for long distances
Disadvantages: Very expensive
76Network Interface CardDevices using wireless needs NICs
It is the hardware for receiving wireless signals
its built into modern day devices
It is connected to the NAP
77Network Access PointLots of places offer NAP
Its where devices can connect to the internet
78Client Side ProcessingClient Side is viewing web pages on your device client
web pages have ,lots of features that are interactive
Interactivity is made by using client scripts written in language using Java Scripts
The client scripts are run by browsers to display the effect
79Use of Client Side processingHover Image - This effect makes image change when you hover your mouse over the image. This is made by the client script
Slider - Another use is slider where u click or swipe to see images
80Advantages of Client side processingSpeed - Processing is faster because data does not need to travel back to the server across the internet
Security - Data cannot be intercepted on the client the same way it can when data is transmitted back to the server across the internet
81Disadvantages of CSPBrowser Specific - Different browsers process client scripts inc different ways which means a web dev cannot be sure how their website would appear of a different browser
Computer Speed - If the computer speed is slow the interactive feature swill not be processed fast enough
82Server Side ProcessingProcessing data at the back end on the web server
its done using special server scripts written in server-side languages such as PHP
This happens after you do something on a web page
Adv: Speed, Security
DisAdv: Browser Specific, Computer Speed
83Uses of Server Side ProcessingSubmitting a web form
Submitting a web search
84Advantages of Server Side Processing
85Disadvantages of Server Side Processing
86Database Table Field RecordData Is a structured collection of data
A table stores a set of data e.g details of students in school
A field are the columns in a table e.g surname
A record is one row that stores data about a single item
87Primary Key Foreign KeyA primary key is a specific field with a unique identifier e.g a Student ID
A foreign key is where your Unique ID appears in another table. Its purpose is to link to the other table
A key field is something with a unique ID
88RelationshipMost databases need more than one table to store all the data
Tables need to be linked or related to creates a relational database
89Data TypesData types are what kind of data is going to be stored in a field
90Data Type: Text Number Date/Time BooleanAny kind of characters, including letters and numbers e.g Your username contains RA1H4N
Number: Numerical Values e.g 1.5
Date/Time: 01/04/03
Boolean: One of two values, such as yes/no or True/False
91Database Table Table ID 16 Records 5 Fields
92Online DatabaseOnline Database means a database that could be access around the world
Websites Uses An online database e.g easy jet.com
93Local DatabaseLocal Database means a database held inside a network to keep it secure.
Smaller companies use Local
e.g Your local GP contains your data in a database on site
94DBMSDatabase Management System
This is a software that allows you to create and use your own database
It creates tables and fields and allow you to search and sort data
95SQLStructured Query Language
SQL is the language used by the DBMS to create and search a database
It has Data definition Language (DDL) to set up the tables
Also Data Manipulation Language (DML) for updates and search queries
96HTMLHTML is the language for making web pages
It uses special tags to tell the browser how to display the content of a web page
97HTML tags
98/ahyper link reference
Create a list
Defines unordered (bullet ed) list
To contain web content
Show the text the user sees
99More tagsThese are for making a table