1.3 Exchanging Data Flashcards
Compression, Encryption and Hashing Databases Networks Web Technologies
1
Q
What name is given to public and private keys used in asymmetric encryption?
A
- Key pair
2
Q
Name the two categories of compression
A
- Lossy
- Lossless
3
Q
In which type of compression is the quality of a file not degraded?
A
- Lossless
4
Q
What is the purpose of encryption?
A
- To keep data secure during transmission
5
Q
Name one type lossless compression
A
- Run length encoding
- Dictionary encoding
6
Q
In which form of encryption do the sender and receiver share the same private key?
A
- Symmetric encryption
7
Q
How many keys are used in asymmetric encryption?
A
- Two (one public and one private)
8
Q
If person A wants to send a message to person B using asymmetric encryption, which key should they use to encrypt the message?
1) A’s public key
2) A’s private key
3) B’s public key
4) B’s private key
A
3) B’s public key
A message encrypted with B’s public key can only be decrypted with B’s private key, which only B has access to.
9
Q
What is said to have occured when two keys map to the same hash?
A
A collision
10
Q
In which kind of lossless compression are repeated characters replaced by one occurrence and the number of times to repeat the character?
A
- Run length encoding
11
Q
What name is given to the process of turning an input into a fixed size value?
A
- Hashing
12
Q
Which data structure uses hashing to store information with constant lookup time?
A
- Hash table
13
Q
What is meant by compression?
A
- The process of reducing the space required to store a file
14
Q
Name two properties that a hashing algorithm should have.
A
- Low chance of collision
- Quick to calculate
- Output smaller than input
15
Q
What is a relational database?
A
- A database which recognises the difference between entities and uses different tables for each entity.
16
Q
What is an entity?
A
- An item of interest about which information is stored.
17
Q
What is a flat file?
A
- A database that consists of a single file, usually about one entity.
18
Q
What is a primary key?
A
- A unique identifier for each record in a table.
19
Q
What is a foreign key?
A
- The attribute which links two tables together
20
Q
What is a secondary key?
A
- An index other than the primary key used to search and sort through the database with more convenience and speed.
21
Q
What does capturing data mean?
A
- The process of getting the information that will be stored in the database.
22
Q
What method do banks use to capture data from cheques?
A
- Magnetic Ink Character Recognition (MICR) is used for all of the details apart from the amount which must be entered manually.
23
Q
What does selecting data mean?
A
- Selecting data is the process of removing excess information to extract only the data you require
24
Q
What does managing the data mean?
A
- To manipulate the information collected in any type of way such as through sorting through it or selecting certain parts using SQL.
25
what is the most common language used to manipulate data in databases?
- SQL (Structured Query Language)
26
What is a network?
- Two or more computers connected together that transmit data
27
What is physical topology?
- Physical topology is the physical layout of the network.
28
What is logical topology?
- The topology that describes the flow of data through a network
29
What is bus topology?
- Topology in which all terminals are connected to a backbone cable
30
Name an advantage of the bus topology
- Cheaper to set up
| - Doesn't require any additional hardware
31
Give a disadvantage of the bus topology
- If backbone cable fails, entire network gets disconnected
- As traffic increases, performance decreases
- All computers can see data transmission
32
What is star topology?
- A network which uses a central node to direct the flow data, each terminal is connected to the central node.
33
Give 2 advantages of Star topology.
- Performance is consistent with heavy network usage
- If one cable fails only that station is affected.
- Transmits data faster, so it given performance
- It's not difficult to add new stations
- No data collisions
34
Give a disadvantage of star topology
- Expensive due to switch and cabling
| - If the central switch fails then the rest of the network fails
35
What is a mesh topology?
- A topology in which every node is connected to every other, most commonly found with wireless technology
36
Give 2 advantages of mesh topology
- No cabling cost
- As number of nodes increase, reliability and speed increases
- New nodes automatically get incorporated
- Faster since data doesn't travel through a central switch
37
Give a disadvantage of mech topology
- Need to purchase devices with wireless capabilities
| - Maintaining the network is difficult
38
What are protocols?
Sets of rules defining how two devices communicate with each other.
39
Why are protocols standard?
- Protocols are standard so devices from different manufacturers don't have problems communicating
40
Describe the structure of the Internet
- The Internet is a global network of interconnected networks
41
What does TCP stand for?
- Transmission Control Protocol
42
What does IP stand for?
Internet Protocol
43
What is the function of the application layer during data transmission?
The Application Layer specifies what protocols need to be used to relate the application to what it's being used for.
44
What is the role of the transport layer during data transmission?
- Establishes an end-to-end connection between the source and recipient computers. It also splits up the data into packets.
45
What is the role of the network layer during data transmission?
- Adds the source and destination IP address.
46
What does the application layer do when it receives data?
- Presents data in the form it was sent
47
What does the transport layer do when it receives the data?
- Removes the port number and reassembles the packets
48
What does the network layer do when it receives the data?
- Removes the IP address
49
What does the link layer do when it receives the data?
- Removes the MAC addresses
50
What is a Local Area Network?
- A network spread over a small geographical area/ positioned on a single site
51
What is a Wide Area Network?
A network spread over a large geographical area, usually requiring extra hardware.
52
What does DNS stand for?
- Domain Name system
53
What is DNS?
- The name given to the method of naming internet resources. (.com, .uk etc)
54
What is circuit switching?
The process of creating a direct link between two devices and transferring data the entire duration of the link.
55
What is a requirement of circuit switching?
- The transfer and download rates must be identical on both devices.
56
What is packet switching?
- A method of communicating packets of data across a network
57
Give an advantage of packet switching
- Multiple methods to ensure data arrives correctly
- Multiple methods to arrive to destination, if one breaks you can always go through another route
- Transfer packets over a very large network
58
Give a disadvantage of packet switching
- Time is spent deconstructing and reconstructing the packers
59
Give an advantage of circuit switching
- Data arrives in logical order which results in a quicker reconstruction of data
- Enables two users to hold a call without any delay in speech
60
Give 2 disadvantages of circuit switching
- Bandwidth is wasted during periods when no data is sent
- Devices must transfer and download at the same rate
- Switches introduce electrical interference which can corrupt or destroy data
61
What does the header of a data packet contain?
- The sender and recipient IP addresses
- Protocols being used
- Order of the packets
- The time to live / hop limit
62
What does the packet payload contain?
The raw data
63
What does the packet trailer contain?
- The checksum or cyclic redundancy check
64
What is client-server networking?
- A relationship between terminals (computers) and a single server which allows them to communicate, and share resources.
65
Give an advantage of client-server networking
- Increase security
- Central single backups
- Data and resources can be shared
66
Give a disadvantage of client-server networking
- Expensive to set up
| - Trained staff are required to maintain the network
67
What is peer-to-peer Networking?
- A networking where the terminals are all connected to each other to share resources.
68
Give an advantage of peer-to-peer networks
- Cheaper to set up
- Easy to share resources
- Easy to maintain
69
Give an disadvantage of peer-to-peer networks
- Peer-to-peer networks can be used to contribute towards piracy
- Each computer has to be backed up independently
70
What is HTML?
- HTML is the language/script the web pages are written in
71
What does HTML do?
- HTML allows a browser to interpret and render a webpage
72
What is a tag in HTML?
- HTML code is made up of tags, tags are the names given to values written within angle brackets i.e.
73
What is an identifier selector?
An identifier selector is a value that hollows a hashtag
74
What is a class selector?
- A class selector is a value that follows a full stop
75
What is CSS?
- CSS is a script/language like HTML except it's used to describe the style of a webpage
76
What are the names of the two methods of applying CSS?
- Internal/embedded CSS
| - External CSS
77
Where do you write internal CSS?
- It's placed inside the style tags and is entered directly within the HTML document
78
Where do you write external CSS?
- You write it in a separate document
79
How do you use external CSS in your HTML code?
- You use the tag
80
What is JavaScript?
JavaScript is a language used on webpages to add interactivity
81
Is JavaScript interpreted or compiled?
- Interpreted
82
What is a search engine?
- A search engine is a program that searches through a database of internet addresses looking for a resource based on a criteria set by the client/user.
83
What software does a search engine use?
- Web Crawlers
84
What does a web crawler do?
Travels across the internet collecting keywords and phrases from a web page and adding it to an index of web resources.
85
What is the page rank algorithm?
- The algorithm used to determine the order used when showing web results for a search engine query
86
What factors determine a page rank?
- The number of incoming links it has from other web pages
| - The page rank of the web pages that link to it
87
What is server side processing?
- Server side processing is when a client sends information to a server for processing
88
What is client side processing?
- Client side processing is when information is processed on a local device for processing
