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Revision Flashcards Learning Aim B
Cards in this deck (109)
- 1The InternetThe internet is a global network
of interconnected computers that
allow 'packets of data' to be
exchanged between computers
and devices. - 2ClientA client is a computer or device that
uses services provided by a server.
The computer used to access the
internet is a client. - 3RoutersRouters are devices that route (direct)
data traffic through a network. They
are intelligent and will try to find the
best route. - 4BackboneA 'big' cable that is often fibre-optic
that connects a large number of devices
in the 'core' of the internet. - 5ServerA server runs a special software to serve other computers. Different types include file, print, web and email servers.
- 6CablesCables form the connection between
all the hardware. Includes all kinds
of cables such as fibre and telephone
lines. - 7ISP (Internet Service Providers)An ISP provides connection to
the web, email and VoIP.
It would be too expensive to access
the internet directly so the ISP gives
an easy way for connection. - 8ISP (Internet Service Providers)An ISP might provide connection to
one 'client' or a network of 'clients'.
For example, a home network or a business network. Examples of an ISP
are Sky, BT and Virgin Media. - 9PoP (Point of Presence)A point of presence is an access point
to the internet. A ISP might have
several PoPs to allow good access to
the internet. - 10NAP (Network Access Points)A network access point is where
different networks interconnect,
such as your home network onto
the internet. - 11Network diagram
- 12Network diagram
- 13LAN (Local Area Network)A LAN is a network on a site, like
a school, or one building, such as
an office block. - 14WAN (Wide Area Network)A WAN is a network that spans the
whole region, or country or globe,
e.g. the Internet. - 15Dial-upA wired connection via
modem and phones - 16Advantages of dial-up- Can use existing telephone wires.
- Gives connection where
broadband is not available. - 17Disadvantages of dial-up- Older technology can give poor reception.
- Usually slower than other methods.
- Conversion between digital
analogue can cause errors. - 18BroadbandA wired connection via a
broadband supplier. - 19Advantages- Better reception and
speed than dial-up. - 20Disadvantages- Wired, so has to be used on
a stationery computer.
- Broadband is not available in
many rural areas - 21WirelessConnects without using cables.
- 22Advantages- Not fixed to a stationery computer.
- Can be used whenever wireless
internet is available. - 23Disadvantages- Needs to have
wireless internet available.
- Can be less secure than wired.
- Tends to be slower than wired. - 24Bandwidth How we measure the speed of internet connection.Bandwidth is how much capacity there is to carry digital data as 1s and 0s. It's measured in bits per second. High bandwidth means more data can be moved, so giving a faster internet connection and a higher transmission rate.
- 25Download speed examples
- 26Protocol meaningSet of rules that allow computer
systems to connect with different
systems to transfer data. - 27HTTP (Hyper Text Transfer Protocol)HTTP is a set of rules that handle
what we do on the web. It handles
your request to load a page from a
web server. It also handles the response
to download a web page and all its
files to your computer. - 28HTTPS (Hyper Text Transfer Protocol Secure)Data in the web page is scrambled
before sending across the internet. So,
if data is intercepted, it can't be understood. It protects your privacy
from 'hackers'. - 29FTP (File Transfer Protocol)An old protocol that was invented before the web was born. It is still used to upload and download files from a server. It is often used by web developers to transfer files to their web server. To use FTP, usually a username and password is required.
- 30TCP (Transmission Control Protocol)Responsible for breaking data into
packets and assembling the packets
again when they arrive. - 31IP (Internet Protocol)Responsible for handling the
routing the packets- addressing,
sending and receiving packets
over the net. - 32How the web works
- 33BrowserWeb pages are accessed through
browsers. They are applications that
allow a user to enter a URL and view a
web page. The browser reads the HTML code and displays the page. - 34HyperlinksThe web works because of hyperlinks.
They connect web pages together.
When a hyperlink is clicked, a user is
taken to another page on the site or
taken to another website. - 35Web serversWebsites are stored on web servers.
When you access a web page through
a browser, the page is temporarily downloaded onto your computer. It
is the web page's job to deliver the
web page requested. - 36URL (Uniform Resource Locator) example
- 37A URL is an address for a web pageComponents of a URL
Protocol- Tells the browser what to do
with the URL. Domain name- The name
of the website. Path- Points to a
specific web page. - 38Search engines are special websites that allow users to find data on the internet.
- 39How search engines workA user enters keywords into the
search engine. The search engine searches its index which is its database of web pages. The results are displayed in order of popularity. The 'sponsored links' will also be placed at the top.
The more a company pays, the more likely it is to appear in the search results. - 40Web crawlers (Spiders) Automated programs that are used to collect details of websites.Spiders look around the web for
new or updated pages and log them
into the search engine's database
which is called the index. - 41Smart searching with operators.By using "quotes" the search engine will search for an exact set of words.
A -minus in front of a word will exclude all results that include that word. - 42Smart searching with operators.By putting a *star in front of a word,
the search engine will find results with
all variations of the word (wildcard).
Using OR in between two words, it will
find the one keyword or the other. - 43Emails (Electronic mail)They are sent from a sender's outbox
and received in a recipients inbox.
The sender and the recipient do not
have to be online at the same time. This
is useful when sending emails to
people in different global time zones. - 44Email - Store and forwardEmails are stored on servers
and then forwarded to the receiver-
so it's called 'store & forward'. - 45CC / BCCCC stands for carbon copy which
means you can send the same email
to someone else. BCC stands for blind carbon copy which means that you can send the same email to more than one person but the recipients won't know
that someone else has the email too. - 46Benefits of email - AttachmentsYou can attach multiple files to
the email such as images
or documents. - 47Benefits of email - CopyUse cc to send copies to other
people. Or use bcc to hide
addresses from others. - 48Benefits of email - Contacts'Address books' store contacts and
you can also use distribution
lists to email lots of people
simultaneously. - 49Benefits of email - Delivery speedEmails usually arrive in
seconds - much faster than
traditional post. - 50Benefits of email - WebmailGmail and Hotmail use
cloud servers so emails can
be accessed anywhere. - 51Drawbacks of email - Junk mail/ spamSpam or 'junk' email has
become a massive problem. - 52Drawbacks of email - PhishingFake emails designed to
trick people to give
personal details. - 53Drawbacks of email - Viruses (from attachments)Attachments can contain
code designed to harm
your computer. - 54Drawbacks of email - Delayed replyEmail isn't real time
so you can't expect an
instant response. - 55Drawbacks of email - No accessNot everyone has email -
or they might not log on regularly. - 56Email protocol diagram
- 57Protocol meaningA protocol allows different software
and devices to communicate so you
can send email on a computer and it
is received on a tablet or phone. - 58SMTP (Simple Mail Transfer Protocol)It pushes outgoing mail to a
server. If there is a problem
sending, SMTP will keep
trying until it's sent. - 59IMAP (Internet Message Access Protocol))Lets you access your email on
a server. When you log on, you
pull email from server. - 60POP3 (Post Office Protocol)POP originally came before web mail
when people used 'email client software' e.g. MS Outlook. You download emails from the server. The emails could also be deleted from the server. - 61Web mail server (All the messages stay on the server)+ Can access email on many devices
+ Email is backed up
- You must have net connection
- Slow service - 62Email client (Emails downloaded to client machine)+ Can access them, even if not online
+ Client software has more features
- Emails lost if computer crashes - 63Packet switchingPacket switching is the process of data being broken into 'packets' before being sent through a network and then reassembled at the other end.
- 64Data packet diagram
- 65Parts of a packet- Trailer- used to check packets
are reassembled correctly.
- Data- This core is the most
important part of the packet.
- Header- The ID is vital to putting all the packets back in order. Addresses tell
where going and coming from. - 66CodecA device or program used for
encoding and decoding between
analogue and digital data. - 67VoIP and Packet Switching
- 68Advantages of packet switching+ Packets choose different routes
so traffic flow is more efficient.
+ Big files can still be sent but
don't clog network.
+ More secure because if hackers intercepts, they will only have
one part of a file. - 69Disadvantages of packet switching- If one or more packets get lost or corrupted during transmission, the whole file will not be received correctly.
- Requires a large amount of RAM (Random Access Memory) to handle large amount of data communication in packets. - 70Data transmission modes- Simplex (one way)Signals go in one direction at a time.
(e.g. remote control to television). - 71Data transmission modes- Duplex (two way)Signals go in both directions at
the same time. (e.g. mobile phones). - 72Data transmission modes- Half-duplex (take turns)Signals go in both directions
but not simultaneously
(e.g. 'walkie talkie' radios). - 73Transmitting bits- SerialBits of data are transferred one at
a time over a wire. - 74Benefits and limitations of serial transmission+ Good over large distances.
- Complex because data has to be
broken into individual bits. - 75Transmitting bits- ParallelBits of data are transmitted simultaneously- a whole byte can
be sent at the same time. - 76Benefits and limitations of parallel transmission+ Faster because more bits
transferred per second.
- Only for shorter distances
(e.g. 5 metres) - 77UTP/ STP cables Unshielded twisted pair/ shielded twisted pairContains pairs of copper wires
twisted together. Used for LAN's
(Large Area Networks). - 78Advantages of UTP/ STP+ Cheaper than other methods.
+ Reliable
+ Shielded cables has a protective
layer to protect data signal
from interference - 79Disadvantages of UTP/ STP- Slow
- Low capacity
- Used over short distances
- Data can be interfered if near another
digital device - 80Co- axial cables- A solid copper wire with
thick shielding
- Used mainly to connect
TVs with aerial - 81Advantages and disadvantages of co- axial+ Reliable
- Slow and has a low capacity
- Used over short distances
- Thick and physically inflexible
- Susceptible to noise - 82Fibre- optic cables- Strands of data carry
data as light.
- Used for the backbone
of the internet. - 83Advantages and disadvantages of fibre- optic cables+ Fast
+ Used over long distances
+ Little interference
- Used for the backbone of
the internet - 84Wireless transmission methods- Using invisible wavesData is transmitted wirelessly using different types of waves from the electromagnetic spectrum.
- 85Infrared (e.g. TV and remote)- Uses infrared light to transmit data
- Very high frequency light - 86Advantages and disadvantages of infrared waves+ Reliable
- Short range
- Devices must be in line with light
- Can suffer from interference - 87Microwave (e.g. Bluetooth)Uses waves with short wavelengths
to transmit data - 88Advantages and disadvantages of microwaves+ Good for medium distances
- Can suffer from interference with
other devices (e.g. a microwave that's
near the computer device) - 89Satellite (e.g. GPS- Global positioning system)Uses satellites in space to
relay data between points on
Earth. - 90Advantages and disadvantages of satellite waves+ Good for very long distances
- Very expensive - 91Client scripts- Interactivity- Client side is viewing web pages
on your client device.
- Today's web pages have lots of
features that are interactive. - 92Client scripts- Interactivity- Interactivity is achieved using
client scripts written in a
language called JavaScript.
- These client scripts are run by your browser to display the interactive effect. - 93Advantages of client- side processing+ Speed- Processing is faster for the client because data does not have to travel back to the server across the internet.
+ Security- Data cannot be intercepted on the client in the same way it can be when data is transmitted back to the server across the internet. - 94Disadvantages of client side processing- Browser-specific- Different browsers process client scripts in different ways, therefore a web developer cannot be sure how their website will appear on a client's screen. - Computer speed- The web developer is relying on the speed of the client computer to deliver the interactive features, so if that is slow then the processing will be slow.
- 95Server- 'Back end' processing- Server side means processing data at the 'back end' on the web server.
- It's done using the special server scripts written in server-side languages.
- All this usually happens after you've done something on a web page. - 96Advantages of server- side processing+ Servers are powerful computers- A web server is likely to be way more powerful than a client computer, so it can process data faster.
+ No browser involved- Servers don't use browsers so there are none of the difficulties you get on the client with different brands - 97Disadvantages of server- side processing- Security- When data is sent back
from the client, it has to travel across
the internet where there is more
risk of security threats.
- Overloading- If a lot of users are asking the web server to process data, it could overload the server and cause it to crash. - 98What is a database?- A database is a structured collection of data.
- A table stores a set of data. - 99Components of a database table- A record is one row that stores unique data about a single item.
- A field are the columns in a table that uniquely identify someone.
- The key field is a special field with a unique identifier.
- A foreign key links to another database table. - 100Relational databases- Most databases need more
than one table to store all the data.
- So the tables need to be linked to
create a relational database. - 101Data types and uses- Says what kind of data is going to be stored in a field- Text- Any kind of characters, including letters and numbers (e.g. names).
- Number- numerical values (e.g. salary)
- Date/ time- dates and times
(e.g. dates of birth)
- Boolean- One of two values
(e.g. yes/ no or true/ false) - 102Database table example
- 103Local databases-Local means a database held inside
a network to keep it secure.
-Features of a local database such
as a school's database might include: information of the staff and the
students such as names, salaries
and dates of birth.
- It can only be accessed from one location. - 104Online databases-Online means a database that could be accessed around the world.
- Shops such as Argos and social networks use databases.
- The database is stored on the server side and the data is sent with the web page when you load it.
- A feature of a shop's database might be information of the stock in store.
- It can be accessed from anywhere. - 105DBMS (Database Management System)- A DBMS is a software that allows you to create and use your own database.
- It creates tables and fields and allows you to search and sort data.
- It handles security to prevent unauthorized access.
- It can also allow for different levels of access for different users. - 106SQL (Structured Query Language)- SQL is the language used by a DBMS to actually create and search a database.
- It has a Data Definition
Language (DDL) to set up the tables.
- And it has a Data Manipulation Language (DML) for updates and search queries. - 107Hyper Text Markup Language (HTML)- It is the language for
making web pages.
- It uses special 'tags' to tell
the browser how to display the
content of a web page. - 108Examples of HTML 'tags'= Makes text bold
= Makes text italic
= Displays text as a paragraph
= Inserts an image
= Creates a hyperlink
= Shows what the user will see - 109Examples of HTML 'tags'= Lists an item
= Used for an unordered list
= Tells the browser it's
a HTML document
= Defines the document's body
= Makes a heading on the web page
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- GCSE IT Flashcards on Revision Flashcards Learning Aim B, created by Saimah Meah on 04/11/2019.
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