2 Comunications and the Internet Flashcards
Chapter 2
Cable types
fibre optic cable
twisted pair cable made of copper
coaxial cable with a metal core
Communication types
Simplex
Duplex
Half-Duplex
Data transmission types (from technical point of view)
Electrical pulses
light pulses
Wireless signals
Types of wireless signals
radio signals
micro-wave signals
infrared waves
list data transmission types, which one is the most used.
serial transmission - most used;
parallel
what transmission type is recommended for long distance and what transmission type is recommended for short distance.
long distance - serial transmission
short distance - parallel transmission
Describe serial port pin usages
Two pins are used for data transmission (in/out). The other pins are used just for controlling the port.
Which port type (serial and parallel) is bigger
Parallel port is bigger.
Advantages and disadvantages of parallel data-buses
Advantage: speed
Disadvantage: it takes up place
What is a data bus and where is it used?
A data bus is a cable with a lot of wires and is used inside the computer to connect internal hardware components, for example CPU and RAM.
USB
Universal Serial Bus
Types of peripheral joining
Permanent joining
Plug in cable
Wireless connection
IC
Integrated Circuit
Transcription error
error when copying data, missing or wrong data
Transposition error
Data was copied in the wrong order
ARQ
Automatic Repeat reQeust
The transmitter sends the data packet till it gets a confirmation from the receiver.
Parity check types
even parity and odd parity
With even parity if in a byte there are four 1s what will be the parity bit?
0
What are the limitations of parity check
If there are 2 errors the errors might not be spotted
transposition errrors are not spotted.
Calculate the check digit number with the simple methode for;
4538
4327
What desadvatage has this kind of check?
(4+5+3+8)=20 -> Check Digit X
(4+3+2+7)=16; 16/10=1.6 ->Check sum digit 6
Transposition errors are not identified.
Check dgit calculation with the Luhn methode.
Calucate for 56783
Every second digit is multiplied by 2, and the total must be an exact multiple of 10
Calculate Check digit with the ISBN-10 methode.
Calculate for: 78394
Every digit is multiplied by it,s position in the number and for the check digit is used mod 11.
Calculate the check sum for the number: 566429
32
What do you need to connect to the Internet?
A data transmission connection (wired or wireless)
Internet software
Shared protocols
What does ISP stand for and what does it do?
ISP stands for Internet Service Provider and it provides the following:
To send signals between the Internet and your computer.
It provides email services
Last but not least it can also host web pages
What are protocols?
Protocols are communication standard rules about how data is turned into signals.
What is a web host
A web host stores the information you want to publish on the internet and publishes it for example wix. In wix you make a web site and if you want to publish it wix does it for you.
The meaning of www and what is it?
World Wide Web, it is the colection of all the webpages in the world.
In what program is a webpage written
HTML
3 examples of webpages.
Amazon, youtube and wikipedia.
What is a web server.
It is a computer that is permanently connecred to the Internet and it hosts web sites.
What is a URL
A URL is the name of a web page.
3 exampels of web browsers.
Internet Explorer
Firefox
Chrome
What is a hypertext
A hypertext is text that is linked to another web page.
Give and example of a tag
<h1>Hello my name is Vilmos</h1>
What is HTTP
HTTP is the protocol that makes hyperlinks work.
HTTPS
Hypertext Transfer Protocol Secure. It has extra features: authentication and encryption.
How do you make sure that the website isn’t fake?
If it has https at the beginning of the URL.
What is a cookie?
Cookies are saved on your computer, to learn key data about what you do on the browser so it shows data that might be relevant for you or setting you saved.
What is TCP?
Transmission Control Protocol controls how data packets are transmitted along the internet.
What is IP?
Internet Control makes shure that the date packet gets to the right destination.
What does URL stand for?
Uniform Resource Location
What is an Anti-virus
It is a software that scans your computer for any malwares and deletes them
What are Spams?
Spams are bulk and unwanted emails.
What is the Internet Filter doing?
An Internet filter blocks unsuitable content
What is a firewall?
The firewall is a software that makes sure that no malwares get into your computer.
What do computer viruses do?
Delete files and make your computer do unwanted actions.
What is a spyware?
Spyware is a special kind of malware that records everything you do on your computer.
List the types of malwares and say what they do?
Virus: this is malware that hides itself inside another file.
Worm: Has its own file and it copies himself to other computers across the network.
Trojan: Disguised as a good file.
Rootkit: changes your operating system so that it won’t be spotted.
Backdoor: switches of the security to let other malware in.
What does Hacking mean
Using links between computers and make changes on them without permission.
What is the main protocol system of the internet (allias and extended name)
TCP/IP
TCP - Transmission Control Protocol
IP - Internet Protocol (Address)
How large is an IP address?
It is very large 128 bits.
What is DNS and how does it work?
Domain Name System - Is an automated data base of all the Internet servers in the world.
What is the difference DNS and Domain Name?
DNS is the data base of all the domain names and the domain name is the name of the server that hosts the website.
What are the components of the URL? Please list the components in the right order.
- The name of the protocol (http, https).
- The domain name
- Path name
- Sometimes extra details are added to the end.
What is .com
Top-level-domain code.
Who maintains top-level-domains and how many domains there are at the moment.
Internet Assigned Numbers Authority (IANA) there are over 1000
Who maintains top-level-domains and how many domains there are at the moment.
Internet Assigned Numbers Authority (IANA) there are over 1000
MAC address
Media Access Control - it identifies the device itself
What is the difference between IP address and MAC address.
MAC address is a unique number that identifies a device. This number is issued at the moment of production of the device.
IP address is a number allocated by the DNS server of the network.
How are MAC addresses shown
Usually in hexadecimal form.
What is a web site?
Collection of web pages
What is a web address?
A web address is the name of the website and hte technical name is URL.
What is a web browser and how it works.
Its a software that lets you look at web pages.
- Gets the web server name from the URL.
- Transfers a copy of your web page on to your computer.
- Displays the webpage.
What is the difference between a web browser and a search engine.
A web browser is a software installed on your computer to show websites.
A search engine is a data base and shows the results through its website.
What is HTML? Describe.
Hypertext Markup Language.
The text document is marked with pairs of tags and the browser will format the text based on the tags.
Types of HTML tags.
Structure: Control the layot of the webpage
Presentation: Controls the formating of the webpage
What is CSS?
CSS is a file which stores the style commands that can be used in your web pages.
