Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

comp sci 1 > Exchanging Data 1.3 > Flashcards

Exchanging Data 1.3 Flashcards

1
Q

Name the two categories of compression

A

Lossy and lossless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Explain lossless compression

A

lossless compression reduces the size of a file without losing any information

The original file can be recovered from the compressed
version

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Explain lossy compression

A

lossy compression reduces the size of a file while also removing some of its information

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the purpose of encryption?

A

To keep data secure during transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Name types of lossless compression

A
  1. Run Length Encoding
  2. Dictionary Encoding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Explain Run Length Encoding (RLE)

A

RLE is a method of lossless compression in which repeated values are removed and replaced with one occurrence of the data followed by the number of times it should be repeated

For example, the string AAAAAABBBBBCCC could be represented as A6B5C3 since ‘A’ is repeated 6 times etc..

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When would and wouldnt you use run length encoding?

A

You would use run length encoding if there are many consecutive values. if there arent many it would not be useful

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain Dictionary Encoding

A

Frequently occurring pieces of data are replaced with an index and compressed data is stored in a dictionary

The original data can then be restored using the dictionary.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When would dictionary encoding be used?

A

passages with repeated phrases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is symmetric encryption?

A

Both the sender and receiver share the same private, This key is used for both
encrypting and decrypting data

If the key is intercepted during the key
exchange then any communications sent can be intercepted and decrypted using the key.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is asymmetric encryption?

A

Both parties have a public and private key, where the public key is used for encryption and the private key is used for decryption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

If person A wants to send a message to person B using asymmetric encryption, what key should they use to encrypt the message?

A

Person B’s public key

A message encrypted with B’s public key can only be decrypted with B’s private key which only person B has access to

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is it meant by compression?

A

Compression is the process of reducing the space requires to store a file

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Hashing?

A

A technique used to store and retreive data in a table by using a unique key. it is used ti speed up searches and comparisions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Name two properties that a hashing algorithm should have

A
  1. Low chance of collision
  2. Quick to calculate
  3. Output smaller than the input
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a Relational database?

A

a relational database is a type of database that stores data in tables, which are related through common fields

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is an entity?

A

An item of interest about which information is stored

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is a flat file?

A

A database that consists of a single file usually about one entity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a primary key?

A

A unique identifier for each record in a table

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a foreign key?

A

The attribute which links two tables together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a secondary key and what is it for?

A

A key that is indexed to allow for faster searching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is normalization?

A

Normalisation is the process of coming up with the best layout for a relational database

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does normalization try to accomplish?

A
  1. Records can be added and removed easily
  2. Complex queries can be carried out
  3. No redundancy (unnecessary duplicates)
  4. consistent data throughout linked tables
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is an index?

A

An index is a data structure used to look up and access data in a database quickly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are the requirements to be in First Normal Form (1NF)?
It does not have any repeating attributes. All the attributes must be atomic (a single attribute cannot more than one data) e.g. a cell shouldn't have first name and surname
26
What are the requirements to be in second normal form (2NF)?
1. The database is in 1NF 2. There are no partial dependencies (no composite keys)
27
What are the requirements to be in third normal form (3NF)?
1. The database is in 2NF 2. There are no non-key dependencies This can be defined as saying - 'All attributes are dependent on the key, the whole key, and nothing but the key'
28
What does SQL stand for?
Structured Query Language
29
What is SQL?
A declarative language used to manipulate databases
30
What is referential integrity?
Referential integrity is the process of ensuring consistency, as it makes sure that information is not removed if it is required elsewhere in a linked database
31
What is a transaction defined as?
A transaction is a single operation executed on data
32
What does ACID stand for
1. Atomicity 2. Consistency 3. Isolation 4. Durability
33
What does atomicity (in ACID) mean?
A transaction will be processed completely or not at all
34
What does consistency (in ACID) mean?
A transaction must maintain referential integrity rules between linked tables
35
What does Isolation (in ACID) mean?
will ensure that each transaction will be isolated and dealt with in a way that does not affect others
36
What does durability (in ACID) mean?
Once a transaction has been executed it will remain, regardless of the circumstances
37
What is record locking?
Record locking is the process of preventing many people to access a record
38
What is the name of an issue that can happen as a result of record locking?
Deadlock
39
What is redundancy
The process of creating more than one copy of data in a physically different location
40
What is a network?
Two or more computers connected together to transmit data
41
What is physical topology?
The physical layout of the network
42
What is logical topology?
The topology that describes the flow of data through a network
43
What is bus topology?
A topology where all terminals are connected to a backbone cable
44
What is star topology?
A network where the central node directs the flow of data, each terminal is directly connected to the central node
45
State two advantages of the bus topology
1. Cheaper to setup 2. Doesn't require any additional hardware
46
State two disadvantages of the bus topology
1. As traffic increases, performance decreases 2. All computers can see data transmissions 3. If backbone cable fails, the entire network is disconnected
47
State two disadvantages of the star topology
1. If the central switch fails the rest of the network fails 2. Expensive due to switch and cabling
48
State two advantages of the star topology
1. Transmits data faster, so the performance is better 2. If one cable fails only that station is affected 3. Not difficult to add new stations 4. No data collisions
49
What are protocols?
Protocols are a set of rules defining how two devices communicate with each other
50
Why are protocols standard?
So that devices from different manufactures are able to communicate
51
Describe the structure of the internet
The internet is a global network of interconnected networks
52
What does TCP mean?
Transmission Control protocol
53
What are the four layers of the TCP/IP protocol stack?
1. Application layer 2. Transport layer 3. Internet layer 4. Link Layer
54
What is the function of the application layer?
The application layer specifies what protocols need to be used
55
What is the role of the transport layer?
1. Splits up data into packets 2. Establishes end-to-end connection
56
What is the role of the network layer?
Add the source and destination IP addresses
57
What is the function of the link layer?
Adds the MAC addresses to the packets
58
What is a Local Area Network?
A network spread over a small geographical area
59
What is a Wide Area Network?
A network spread over a large geographical area
60
What does DNS stand for?
Domain Name System
61
What is DNS?
A system used to name and organise internet resources. Domain names are much easier to remember than IP addresses, which is why they are used to link to servers across the world
62
What is the role of a DNS?
The role of the domain name system server (DNS server) is to translate these domain names into IP addresses when we wish to access a website.
63
What is Circut switching?
The process of creating a direct link between two devices and transferring data the entire duration of the link
64
What is the requirement for circuit switching
The transfer and download rates must be identical on both devices
65
What is packet switching?
A method of communicating packets of data across a network
66
Give two advantages of packet switching
1. Multiple methods ensure data arrives correctly 2. Transfers packetes over a large network 3. Mulitple methods to get to a destination, if one method breaks you can go another route
67
Give an advantage of circuit switching
1. Data arrives in order which means data will reconstruct faster 2. Allows two people to call without any delay
68
Give a disadvantage of circuit switching
1. Devices must transfer and download at the same rate 2. Bandwidth is wasted during periods when no data is sent
69
What is the purpose of a firewall?
To prevent any unauthorized access to a network
70
What is a firewall made up of?
1. Firewall software 2. Two network interface cards
71
What is the function of a network interface card?
It connects a computer to a network
72
What is the function of a router?
A router connects two networks together
73
What is client-server networking?
A relationship between terminals(computers) and a single server, which allow them to communicate, and share resources.
74
Give an advantage of client-server networking
1. Increased security 2. Data and resources can be shared
75
Name a disadvantage of client-server networking
1. Expensive to set up 2. Trained staff are required to maintain the network
76
What is peer-to-peer networking?
A network where all terminals are connected to each other to share resources
77
Give two advantages of peer-to-peer networks
1. Cheaper to setup 2. Easy to share resources 3. Easy to maintain
78
Give two disadvantages of peer-to-peer networks
1. Each computer needs to be backed up independently 2. Files and resources are more difficult to share

comp sci 1 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions