Computers π» | Welcome to the Internet! | 5.1 Flashcards
Define internet
The world-wide interconnection of networks
Define the World Wide Web
(WWW)
A massive collecion of webpages based on http and https
What is the difference between the WWW and the internet?
The internet is the infrastructure, which is the connection of many networks. The WWW is a collection of multimedia webpages and other information on webpages.
What is the difference between the WWW and the internet?
The internet is the infrastructure, which is the connection of many networks. The WWW is a collection of multimedia webpages and other information on webpages. delete later
What does TCP stand for?
Transmission protocols
What does IP stand for?
Internet Protocols
How are https protocols written?
Using hypertext markup language (HTML)
Web resources are accessed by __
Web browsers
Define URL
A text-based address for a web page
Define web broswer
Software that connects to a domain name server (DNS) to locate IP addresses; a browser interprets HTML web pages sent to a userβs computer so that the user can read documents and watch multimedia
Define HTML
The language used to design, display and formal web pages, and to write http(s) protocols
What does HTML stand for?
Hypertext mark-up language
What does URL stand for?
Uniform Resource Locator
What can a URL contain?
- Protocol
- Domain host
- Domain name
- Domain type
- Web page/file name
What is the format of a URL?
protocol://websiteaddress/path/filename
What does the website address contain?
- Domain host (www)
- Domain name (site name)
- Domain type (.com, .org, etc)
- Sometimes, country code (.uk, .de, etc)
What does HTTP stand for?
Hypertext transfer protocol
Define HTTP
A set of rules that must be obeyed when transferring files over the internet.
Define HTTPS
Hypertext transfer protocol secure - http with extra security, such as SSL, applied
In what situation does the protocol change from http to https?
When some form of security such as SSL or TLS is used
List the functions of a web browser
- Convert HTML code
- Display web pages
- Check if a website is secure
- Request web pages from a web server
- Send URL/domain name
- Runs active script
- Store history/favourites/bookmarks
- Create tabs
What is the main purpose of a web browser?
To render HTML and display web pages
Define Domain Name Server (DNS)
A server that looks up domain names for websites in order to find the IP addresses that a computer needs to locate the web servers
Explain the process of how a web page is located and sent back to the use, in the case where the IP address is not found in the first DNS server
- User opens their browser and types in the URL. The browser asks the DNS server (1) for the IP address of the website
- If the DNS server (1) canβt find the URL in its database or chache, it sends out a request to a DNS server (2)
- The DNS (2) server finds the URL so it can map it to the IP address, sending it back to the DNS server (1), which then puts the IP address and its associated URL back into its cache or database
- The IP address is sent back to the userβs computer
- The computer now sets up a communication with the website server and the required pages are downloaded
Explain what a DNS server does if it cannot find the matching URL for the IP address in its database
In this case, the DNS server sends out a request for a second DNS server to find the URL. This server maps the URL to the IP address, sends it back to the first DNS server, which sends it back to the userβs computer
In what two ways can a DNS server store URLs and IP address?
- Using a database of URLs and matching IP addresses
- Using its cache
Define cookies
A text file sent from a website to a userβs browser; used to remember user preferences each time they enter the website
What type of file is a cookie?
A text file
What are the two types of cookies?
Session cookies and Persistent cookies
Define session cookie
A cookie that is stored temporarily on a computer; it is deleted when the browser is closed or the website session ends
Define persistent cookie
A cookie that is stored on the userβs hard drive and only deleted when the expiry date is reached or the cookie is deleted by the user
Define virtual shopping basket
An area of memory in a website where items a items a user wishes to purchase are temporarily stoed; items remain in the basket until payment is made or the session has ended
Where are session cookies stored?
In the RAM or temporary memory
Where are persistent cookies stored?
In the hard drive
What type of cookies are used in virtual shopping baskets?
Session cookies
How long do persistent cookies last?
Till the expiration date or user deletion
Why are persistent cookies efficient at carrying data from one website to another?
It removes the need for massive amounts of user data to be stored on the web server itself
What are the uses of persistent cookies?
- Allows the website to remember usersβ passwords, email addresses, and invoice details, so they donβt have to insert all this information every time they visit
- Serve as memory, so the website can recognise the user each visit
- Save usersβ items in a virutal shopping basket/cart
- Track internet habits and usersβ website history or favorites for advertising
- Store usersβ preferences
Define digital currency
Currency that exists in electronic form only, with no physical form - essentially data on a database
What has the development of digital currency enabled?
- Banking online or on a smartphone app
- The online sending of money
How does a centralised digital currency sytem work?
The sender/buyer and reciever each may have their own bank they use. When money is transferred, the bank sends it to the central bank, which then transmits it to the second bank, and to the reciever
What is the drawback of centralisation?
Issues maintaining confidentiality and security.
Define cryptocurrency
A form of digital currency that uses a chain of decentralised computers to control and monitor transactions
Define cryptography
The protection of data/information by use of coding; usually involving encryption and decryption
What are the benefits of cryptocurrency compared to traditional banking?
- Traditional digital currencies are regulated by central banks and governments - making exchange rates influenced by state control. Cryptocurrency rules are uninfluenced by this and decided on by the community.
- Cryptocurrency transactions are publically available, so all transactions are monitored and tracked
- Cryptocurrency uses the more secure blockchain system
Define blockchain
A blockchain is a digital ledger,
that is a time-stamped series of records that
cannot be altered, due to using a number of interconnected computers.
Since blockchaining doesnβt involve a centralised database, where is transaction data stored?
On all computers in the blockchain network
In what areas is blockchain used?
- Cryptocurrency
- Smart contracts
- Research
- Politics
- Education
Define timestamp
when it comes to blockchain
A digital record of the time and data that a data block is created in blockchain networks
What does a single block in a blockchain contain?
- Data
- Hash value
- Previous hash value
What data is often found in a block?
Name of sender and recipient, amount of money, and so on
What is the hash value of a block in a blockchain?
A unique value generated by an algorithm which acts as a fingerprint
What is the purpose of the previous hash value in a blockchain?
To point back to a previous block in the chain
What is the genesis block?
The first block in a blockhain that doesnβt point to any previous block
How does a blockchain prevent tampering?
If the data in one block is changed, the data in further blocks will be invalid as the chain is broken
Define proof-of-work
The algorithm used in blockchain networks to confirm a transaction and to produce new blocks to add to the chain; special users called miners complete and monitor transactions on the network for a reward
What is the purpose of proof of work?
To make sure the process of creating new blocks is slowed down so that a new string of blocks cannot be quickly created
