Data Transmission and Security Flashcards

Question

Modem

Answer 1

stands for modulator/demodulator converts digital signal from computer and converts to analogue signal for phone lines a second modem at the receiving end converts the signal back to digital

Answer 2

A router is a hardware device that allows you to connect several devices to a single internet connection (home setting) Many routers have a WAP (Wireless access point) allowing you to create a wireless access point

Answer 3

TCP (transmission control protocol) - breaks up messages sent over the internet into packets - reassembles packets at the other end - detects errors - resends lost messages IP protocol - routes the individual packets between sender and recipient

Answer 4

HTTP (hyper text transfer protocol) used for accessing and receiving web pages in the form of HTML files on the internet The protocol requests the web server to upload the requested web page to the users browser for viewing HTTPS (secure protocol) encrypts the information so that it can not be hacked

Answer 5

Each file is broken up into packets Each packet is given a header containing: - IP address its going too (Internet protocol) - IP address it came from - Sequence number of the packet - Number of packets in the whole communication

Answer 6

Every device connected to the internet has an IP address eg. 81. 101. 137. 12 Packets are labelled with the senders and the destinations IP address Packets are sent across the internet along separate routes and reassembled at the end

Answer 7

A PC network has a public and private IP address Public IP belongs to the router on your LAN Private IP is accessible only through the LAN ISPs are allocated blocks of IP addresses Once a message arrives at the router of your LAN it will use the private IP address to identify which device requested information

Answer 8

A media access control address is assigned to each Network interface card by the manufacturer. Computers may have 2, one for ethernet and one for wireless or for a phone wireless and bluetooth Hex value eg. 3B:14:E6:39:0A:2C Every network device in the world has a unique MAC address There are 2^48 possible MAC addresses Role of a MAC address: When you request a web page each router along the way uses the MAC address of the next router to send the data packet to the next leg of its journey.

Answer 9

Uniform resource locator is a web page and all are unique WWW. ``` Domains names (TDLs) .uk , .nz etc ```

Answer 10

Domain Name system DNs technology allows you to type a URL into your web browser and it translates the web address into an IP address. There are 13 DNS "root" servers worldwide that keep complete database of all names and IP addresses Lower level DNS servers are owned by ISPs and hold parts of the database When a DNS server receives a request not in its database it will pass it on until reaches one with the matching name and IP address

Answer 11

A cookie is a small data file that a web server puts onto your computer when you visit a website Cookies save any data entered such as registration details, passwords and relevant adverts for you as well as web preferences.

Answer 12

1. User types web address (URL) into browser 2. Browser forwards request to web server to access page 3. Web server acknowledges request and sends HTML source code for the web page to the computer 4. Source code is rendered (translated) into viewable web page

Answer 13

Malware is any software written with malicious intent. - Disrupt computers from their work - Corrupt files - Record key presses and gather information - Gain unauthorised access to a computer or files Not all viruses cause harm, but the ones (most) that do: - limiting hard disk space and memory - destroying or damaging files and data - spamming your address book with contacts - consuming your internet bandwidth Types of Malware: Spyware, gathers information, installs more spyware, sends information back to spyware author, sells to advertising companies or help with identity theft Adware, irritating pop ups, instals itself on a computer, rarely harms Viruses, small program that replicates by inserting itself in other computer programs - attach them self to existing software programs and infect when you run that program - self replicate Worms, a standalone file that does not need a host program to attach itself to Trojans, a non-self-replicating virus that masquerades as a harmless file that you might want to open Ransomware, malware used to lock your computer or access to your flies for which you are then asked to pay a fee to regain access

Answer 14

A virus can compromise a computer and use the host's storage and processing power to perform jobs This computer can then become a part of a Botnet network ( a group of computers secretly cooperating to send spam or cause disruption on a much larger scale) Computers in a botnet can: - send email spam to other users - store and distribute illegal material - perpetrate a Denial of Service attack

Answer 15

Denial of service attack Frequently aimed at company or web servers to overload them or make them crash by: - flooding servers with millions of requests - absorbing 100% of its processor time or memory - using all available bandwidth Attempts to make a network or website unavailable to legit users and the motive is often revenge, blackmail or terrorism

Answer 16

- personal vigilance - scan external devices and drives - anti-virus softwares - firewall software

Answer 17

- detects viruses - deletes or quarantines infected files - commonly finds all malware including adware, spyware, worms and Trojans Works by: - holding a dictionary of snippets used in viruses - scans new files, downloads, external drives on your computer - looks for suspicious codes by comparison - keeps a dictionary of know viruses up to date

Answer 18

- acts as a filter or barrier between your own trusted network and others - only allows certain data packets across that meets set filtering rules

Answer 19

Breaking security defined as unauthorised access to files or data - Exploiting weaknesses in websites or security systems to access data - Guessing default or common passwords - Tricking people into downloading malware to gain access to their computer - Logging in as someone else without their permission In order too: - pure mischief or a challenge - steal money - steal or modify information - for political reasons, expose wrongdoing or revenge on opposing views

Answer 20

Black hat hackers are illegally hacking with criminal intent White hat hackers ethical hackers employed by companies to deliberately find holes in their own security Grey hat hackers look for wholes in other systems and ask for a payment from those systems

Answer 21

Not hacking Illegally accessing program source code to change it or fool it to: - Bypass security or licensing control - prevent software from expiring - unlock features that otherwise would require a subscription

Answer 22

International standard language that all pages can read and all pages are written in. Webpages, webpage code

Answer 23

In a text file containing the content of the website to be displayed by the browser Uses to govern how to present sections of content Stores locations of images that are to be displayed Stores the location of other websites that are linked to using hyperlinks

Answer 24

HTML controls content and function of a web page Cascading Style Sheets control its style and appearance

Answer 25

open <> and close > Websites are made of a head and body

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- different headings (main , sub) : emphasis Click here for more info : link placed in middle line, click to access

Answer 26

# Define the style at the top between tags h1 {colour:blue; text-align: centre} Everything that falls inside the style tag, that html will adopt that style Sector ==> h1 or other Declaration ==> property and value Property ==> colour or other Value ==> blue or other h1 {colour: blue;} To add a CSS style: Define a style for a particular tag eg. h1 or Define a general style and attribute it to a new name eg. #page Attribute style to a

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