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Communicator Badge – Internet - MODULE 6
Training Objective:
The cadet should demonstrate knowledge of and display a practical ability on the Internet, to
the satisfaction of the Squadron Communications Officer.
Enabling Objectives:
To have a satisfactory knowledge of:
a. Simple Website Construction
b. Sending a receiving Emails and attachments accurately
c. Proficiency in the use of Search Engines to find specific resources
d. The use of File Transfer Protocol
e. The use of Web Browsers
To be aware of and explain the use of:
f. Anti Virus and Anti Spyware software
g. Firewalls and their importance in security
h. Passwords and Security
i.
IP addresses, DNS and Routers
Annex B which follows is a simple worksheet which may be used for training and assessment of
this module. It may also be signed off by the cadet’s ICT teacher from school or college.
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Internet Module Practical
Rank _______ Name _________________________
Sqn _______________________
The Internet is made up from millions of computers all over the world that can be connected
together.
Computers that hold web sites and other files are called SERVERS, your PC at home is
known as a CLIENT. Information is transferred between servers and clients as ‘data’.
The way that computers on the Internet format data to talk to each other is known as
INTERNET PROTOCOL, or IP. This is controlled by another protocol called Transmission
Control Protocol – TCP. Internet Protocol Version 4 (IPv4) is the dominant protocol of the
internet. Its successor is IPv6, which is increasing in usage.
A protocol is a bit like a language - the way that strings of data are formatted and transmitted
so that the receiving end understands exactly what the transmitting end sent. By using
different protocols, different types of data may be sent over the same link, and the computer at
the receiving end can decide from the protocol what type of data it is and what it should do
with each packet of that type of data.
All computers on the Internet have a unique identifying address, called an IP ADDRESS,
which looks something like 173.194.67.104 An IP address is a bit like an internet phone
number.
Some IP addresses are fixed, and some change each time that computer connects to the
Internet. These are called static and dynamic IP addresses. To find your IP address when
connected to the Internet go START - RUN and type CMD, press return, then type WINIPCFG
into the box (or IPCONFIG if you are using Windows XP / Vista.) Press return. You may see
your internet IP address or your router-allocated local address (IPv4 address) which will
usually start with 192.168. or 10.0.
My IP address is ___________________
To visit a web site, a URL, or Uniform Resource Locator, is typed into the address bar in
your browser.
For example http://www.raf.mod.uk/aircadets/whatwedo/sports.cfm This URL is made up
from a number of components. http:// is the Protocol to be used, www means it is to be
found on the World Wide Web, raf.mod.uk is the Domain Name, and
whatwedo/sports.cfm is the name of the folder and file where the page is stored, and the file
is written in cfm, or Cold Fusion Mark-up Language.
When connecting your PC’s browser to a web site, the internet first uses a Domain Name
Server (DNS) computer to change the domain name you entered (like
http://www.google.co.uk) into an IP address (like 173.194.67.104). Domain Name Servers are
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usually part of your Internet Provider’s hardware, and are a bit like an automatic telephone
directory, IP addresses are a bit like telephone numbers. The IP address is sent back to your
Browser, which then attaches the information you have requested and sends it out to the
Internet. If the DNS can’t find the IP address, you see a DNS error message on the screen.
A large number of interconnecting packet switches, called routers, then use look-up tables for
the IP address and decide where to route your data on to next, finally connecting your PC to
the distant web site’s server. Routers are a bit like intelligent telephone exchanges.
Web pages can be written in a number of languages, for example Hypertext Mark-up
Language, HTM or HTML or as an Active Server Page. This is why many web pages file
names end in .htm, .html or .asp. There are a number of programming languages which web
pages can be written in.
Once the connection is made from your PC to the server, web page code from the server is
transferred to your PC using Hypertext Transfer Protocol, or HTTP. This code is sent to the
browser running on your PC, gets decoded by the browser and is then displayed on the
screen. You can see the actual code which creates the web page you are seeing by going
‘VIEW’ then ‘SOURCE’ in your browser.
Other protocols transfer other types of information. Data can be uploaded to a web server
using File Transfer Protocol – FTP.
LAN’s and WAN’s
A LAN is a Local Area Network. This is the kind of network that you would have at home or
in an office connecting multiple computers together.
A TYPICAL LAN
A WAN is a Wide Area Network. This is quite simply a collection of LAN’s. Many large
organisations with multiple sites will use a WAN to connect the LAN at each site together
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allowing them to share data with one another. For small LANS the router will also act as a
switch. The Internet is also a WAN.
A TYPICAL WAN
To connect a LAN to a WAN you must have a router, also sometimes referred to as a
gateway. This will be the box you have at home that connects all your computers together and
also connects to the phone line. The router does two jobs, it separates your home network
(LAN) from the internet (WAN) but also allows data to flow between the two so you can
access the internet. Routers often contain a Firewall as well. This can help prevent unwanted
and authorised access from the WAN to the LAN, for example hacker attacks.
The router also controls IP address allocation to the PCs on its LAN. Common LAN IP
addresses begin with 192.68.1.2 or 10.0.0.2 and router IP addresses are often 192.168.1.1 or
10.0.0.1.
Connecting to a Network
There are two different ways you can connect to a network, these are known as wired and
wireless (also referred to as Wi-Fi).
A wired network connection is the simplest and easiest way to connect to a network, you
physically connect a cable from your computer or device into the network switch connecting
you to the network. These cables are commonly terminated in an RJ45 connector and use
CAT5 or CAT6 cable as standard. Hard-wired networks are also known as Ethernet.
An RJ45 connector with CAT5 cable
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A wireless network is easier to setup as you do not have to lay cables and make sure you
have enough fixed connection points available for all the computers.
They both have their advantages and disadvantages. Wired networks are faster and more
secure but are harder to initially set up. Wireless networks are much easier to set up but can
be slower and are less secure. To break into a wired network you need to be physically
connected, but a wireless network you just need to be within range. To protect wireless
networks an encryption system requiring a password and / or ‘key’ is usually enabled. Current
encryption protocols include WEP (less secure) and WPA (more secure).
Point to Note: being connected to a network, wired or wireless does not mean that you are
connected to the internet. These are just ways in which you can connect to a LAN
Connecting to the internet
There are many different ways you can connect to the internet, Dial-Up, ADSL, Cable,
Mobile Broadband and Satellite to name but a few.
Although rarely used nowadays Dial-Up was how people first connected to other remote
computers. They would actually phone the other computer (via a modem at each site) to
access they data they needed. Modem is short for modulator/demodulator, it turns the
computer data into audio signals which can be sent down the phone line, and then recovers
them into data at the far end. Inter-computer use then expanded to allow you to connect to an
ISP (Internet Service Provider) and access the internet. The down side of Dial-Up is that it’s
very slow and when it’s connected to a phone line the same line cannot be used to make
phone calls. Typical speed was 33.6kb/s (kilobits per second). They are still sometimes used
as a backup solution by companies if they were to lose their main internet connection.
ADSL stands for Asymmetric Digital Subscriber Line. This is the type of internet connection
you are most likely to have at home. It is called asymmetric because more bandwidth is
available to carry data downstream to your PC and much less bandwidth is available to carry
data upstream to the internet.
It connects using your normal phone line but unlike dial-up you can use the phone at the same
time. The connection speeds are much faster than dial-up as it uses a digital signal instead of
an analogue one.
The way that the ADSL and your phone share the same connection is by how they use the
phone line. The most common way is splitting the signals using different frequencies, the
voice channel is 0 to 4 kHz, the upstream is 25-160 kHz and the downstream is 250 kHz 1.5MHz. This means that both the modem and your phone can share the same line and not
interfere with each other. To further prevent the internet signals from interfering with your
phone you have to fit ‘microfilters’ to all the devices connected to your phone line, these
have two outputs one for your phone and the other for your modem. They work by filtering the
signals so that anything that is less than 4 kHz goes to the phones and over 4 kHz goes to the
modem. A typical download speed for ADSL is 5000 kb/s.
They are the two most common types of internet connection.
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Large business might have a dedicated internet circuit. This is a Fibre Optic cable which
would run directly from the office building into an ISP’s router. This would allow the company
to have a very fast and reliable internet connection but it would also be vastly expensive.
Local speeds of up to 100Mb/s are available using optical fibres, although the actual speed
can be reduced considerably if non-optical fibre circuits are used in the remote connection
between the sites.
Mobile broadband is another way to connect to the internet. This is also how your mobile
phone connects to the internet. The way you connect to the internet using a mobile broadband
connection works in much the same way as you would when connecting to a wireless network
at home. Your dongle or phone firsts connects to the wireless network, in this case that’s your
network provider (O2, Orange, Vodafone, etc.). Once connected, there is no difference; your
data is passed through the routers of your ISP which in turn allows you to connect to the
internet.
The speeds for mobile broadband are now beginning to match normal ADSL connections so
for a lot of people is their only connection to the internet. The massive benefit of mobile
broadband is the fact you can use it pretty much anywhere you have signal, but that is also its
downfall, if you don’t have a good enough signal where you are (or none at all) you will then
be unable to connect to the internet.
Exercises
On a PC connected to the Internet, go START - RUN (or type RUN in the ‘start search’ box
and press RETURN, then click on the Run icon). Then type in CMD (or try COMMAND).
Press RETURN. You will see a command prompt window. You now need to enter a few DOS
commands.
Type CD\ and press return. This changes the directory to the root directory on the C: drive.
Type CLS and press return. This clears the screen.
Exercise 1
Type PING WWW.NASA.GOV and press return.
This sends 4 special packets of data (called ‘ping packets’) from your PC to the web server
that hosts the NASA web site in America. The NASA computer will send your ping packets
back. The minimum, maximum and average time it takes for the packet to be returned to your
PC is measured and displayed.
You can also see the IP address for WWW.NASA.GOV What is it? ______________
Try pinging WWW.RAFMUSEUM.ORG.UK and WWW.AUSTRALIA.COM Which is the
fastest?
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Exercise 1 answers
Ping times for WWW.RAFMUSEUM.ORG.UK?___
Ping times for WWW.AUSTRALIA.COM?
______ ______
____________
_______ ___ ________
____________
IP address for WWW.AUSTRALIA.COM? ___________________
Exercise 2
It is possible to see the route over which IP data is sent between your PC and the distant web
site. The command TRACEROUTE can trace the route from your PC to the distant web
server. The result shows the time taken, router identification and router IP address for each
router along the link between your PC and NASA’s.
In the DOS box type TRACERT WWW.NEWYORK.COM and press return.
Your screen will fill with responses from each router, and you will see that a large number of
routers have switched the data sent from your PC through to the distant web page server.
Can you see where some routers are located?
Exercise 2 answers
Router names or locations for WWW.NEWYORK.COM
________________
_________________
________________
________________
Type EXIT and press return to close the DOS window
Exercise 3
To bypass the Domain Name Server (DNS), type the IP address http://109.200.19.149 or
http:// 212.58.246.90 (including the full stops) directly into your browser address bar where
you would usually type a www.--- domain name.
Which web site does this connect you to?
________________________________
Exercise 4
Connect to the Internet and start your web browser. Open your favourite search engine.
Q1 Find out what happens at the Davis Monthan an AMARC facility in the USA.
Q1 Answer
______________________________________________________________________
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Q2 Find the URL for the main web site about a Horsa Assault Glider Rebuild Project.
Q2 Answer _________________________________
Q3 Find 2 web site URLs which link to the RAF Museum Cosford web site, but don’t have
‘museum’ in any part of the URL.
Q3 Answers
____________________________ ___________________________
Q4 What is a UK/VRC353?
Q4 Answer
________________________________
Q5 Find a web site which links to http://raf.mod.uk/aircadets/ (Advanced search)
Q5 Answer
_________________________________
Q6 Find the IP address for www.bbc.co.uk
Q6 Answer
__________________________
Exercise 5
Determine what type of internet connection you have at your squadron (if none at squadron at
home instead).
__________________________________ __________________________________
How do you connect to the network at squadron or home?
__________________________________ __________________________________
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Assessment
1. What does IP stand for? _______________________________________
2. What is an IP address?
_______________________________________
3. What is a typical router identification name? ________________________
4. What is the IP address for that router? _____________________________
5. What does DNS stand for?
_____________________________________
6. What is a server? _______________________________________________
7. What does HTTP stand for? ______________________________________
8. What does FTP stand for? _________________________________________
9. What does HTML stand for? ______________________________________
10. What does ADSL stand for? ______________________________________
11. Describe the difference between a LAN and a WAN.
__________________________________ _________________________________
__________________________________ _________________________________
__________________________________ _________________________________
__________________________________ _________________________________
__________________________________ _________________________________
12. Find 3 Boolean search terms that can be used in search engines, and describe what they
do.
_________________ __________________________________
_________________ __________________________________
_________________ __________________________________
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FIREWALL
Use the internet* or other resource to find out what a Firewall is and what it does. Discuss
briefly what a port is on a computer and how a firewall works with ports.
VIRUS
Use the internet or other resource to find out what a computer virus is, how they are sent
between computers and what effects a virus can have. Discuss briefly how a PC can detect a
virus and prevent its effect.
SPYWARE / ADWARE
Use the internet or other resource to find out what spyware and adware is, how they are sent
between computers and what effects they can have. Discuss briefly how a PC can detect
spyware and adware and prevent its effect.
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HTML
The programming language used to write many simple web pages is called hypertext markup language, or HTML.
Visit the 425 (Aldridge) Sqn Duke of Edinburgh web page.
When that page has loaded, right-click on the lower part of the page, then select ‘View source’
or ‘View Page Source’ in the pop-up menu. The code you can see is the HTML for that web
page.
At the top is the header code. This sets information for search engines to use, browser title
bars etc.
Active tags are enclosed in < > brackets, with an opening and closing bracket. The closing
brackets are in reverse order of the opening brackets, and have a forward slash / to close the
activity.
Find out what the following HTML code has been written for, or what it produces in a browser
window:
1)
<META name="Keywords" content="youth, dofe, scheme…"
2) <BODY bgColor=#70BCF0>
3) <P align=center> <img border="0" src="images/DofELogo425_1.jpg" width="528"
height="229"></P>
4) <a href="lower_frame.htm#Link"><img border="0" src="backanim.gif" width="100"
height="32"></a>
* http://en.wikipedia.org/
is a good starting point…
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ISP, DNS,
ROUTERS, WEB
SERVER
Other
ISP’s,
routers,
servers
etc
THE
INTERNET
WEB SITE
SERVER
THE
INTERNET
‘CLOUD’
Router
Router
Router
Router
Router
Router
Router
Router
Router
Router
Router
Router
THE
INTERNET
Router
Other ISP’s,
routers,
servers etc
4
1 – A URL, containing a domain
name, (eg www.425atc.co.uk) is
entered into the browser and is sent
to the ISP
2 – The ISP requests the relevant
domain name server’s IP address
from the Domain Name Server - DNS
2
YOUR
INTERNET
SERVICE
PROVIDER
(ISP)
DNS
DOMAIN
NAME
SERVER
1
ISP
3
YOUR HOME /
SQN ROUTER
3 – The IP address is sent back to the
browser - then a request for the
wanted IP address and file name is
sent back to the ISP
1
4 - ISP sends request for that IP
address / file name to the internet
routers and relays the requested file
back to the browser once found.
Mouse
3
YOUR PC
Keyboard
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