1.3 Exchanging data Flashcards
1
Q
What is compression?
A
the process used to reduce storage space required by a file
2
Q
What is the purpose of compression? (4)
A
-reduce file sizes
-reduce download times
-reduce storage requirements
-make best use of bandwidth (amount of data sent at a time)
3
Q
What are the two categories of compression?
A
-lossy
-lossless
4
Q
What do we mean by lossy compression?
A
a type of compression that reduces sizes of files by removing some of its information e.g. a more pixelated image/less clear audio recording
5
Q
What type of files are used for lossy compression?
A
-sound files
-image files
6
Q
What do we mean by lossless compression?
A
a type of compression where the original file can be recovered
7
Q
What type of files are used for lossless compression?
A
-text files
-executable files
8
Q
What are the two methods to use lossless compression?
A
-run length encoding
-dictionary encoding
9
Q
What is run length encoding?
A
a form of lossless compression where repeated values are removed and replaced with the single data item followed by the number of times it should be repeated
e.g. AAAAABCCC would give A5B1C3
10
Q
What is an inefficiency when using run length encoding?
A
-relies on consecutive pieces of data being the same
- little repetition = little reduction in file size
11
Q
What is dictionary encoding?
A
a form of lossless compression which replaces commonly repeated data with an index and saves the compressed data together with a dictionary that links the frequently repeated data to their corresponding index
e.g. I 1
went 2
to 3
the 4
park 5
. 6
[space] 7
this dictionary would then help decode 17273747576
12
Q
What is something to remember about dictionary encoding?
A
if the compressed data isn’t transferred alongside its dictionary, the data cannot be used
13
Q
What do we mean by encryption?
A
the process of encoding a message so it can be read only the sender and the intended recipient
14
Q
What do we mean by encoding a message?
A
converting the message from plain text to cyphertext
15
Q
What are the two types of encryption?
A
-symmetric
-asymmetric
16
Q
How does symmetric encryption work?
A
-both sender and receiver share the same private key
- key is used for both encrypting and decrypting data
17
Q
How can symmetric encryption by intercepted? (2)
A
-interception of the key
-duplicating the key to have a copy
18
Q
How does asymmetric encryption work?
A
-two keys used: public & private
-public key can be published anywhere but private must be secret (together known as a key pair)
-messages encrypted with public key can only be decrypted with the corresponding private key
19
Q
What is hashing?
A
a process where an input (called a key) is turned into a fixed sized value (a hash)
20
Q
How are keys turned into a hash?
A
uses algorithms called hash functions
21
Q
What is something to know about hashing?
A
-one way process: the output of a hash function cant be reversed to form the key
-the key cant be reversed to gain the passwords
22
Q
What are hash tables?
A
a data structure which holds key-value pairs
23
Q
What do we mean by a collision?
A
when two keys produce a same hash
24
Q
How can we overcome collisions?
A
-storing items in a list under a new hash value
-using a second hash function to generate a new hash
25
What would a good hashing function consist of? (4)
-low chance of collisions
-minor changes in data causing large changes to the hash
-quick to calculate
-provides smaller output compared to the input
26
What is a database?
an organised collection of data
27
What is an entity?
an item of interest about which information is stored
28
What is an attribute?
characteristics of an entity
29
What is a relational database?
a database which recognises the differences between entities by creating different tables for each entity
30
What is a table?
an entity/file
31
What is a record?
a row of data within a table
32
What is a field?
a column of data within a table
33
What is a flat file?
a database that only contains a single table
34
How are flat files written out?
Entity1(attribute1, attribute2, attribute3...)
35
What is a primary key?
a unique identifier for each record (row) in the table
36
What is a composite key?
a primary key composed of more than one attribute
37
What is a foreign key?
an attribute which links two tables together
- exists in one table as the primary key, acts as the foreign key in another
38
What does a secondary key do?
allows a database to be searched quickly
39
What are the different entity relationships possible? (3)
-one to one
-one to many
-many to many
40
Draw a diagram showing the entity relationships
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41
Describe the one-to-one entity relationship
each entity can only be linked to one other entity and vice versa
42
Describe the one-to-many entity relationship
one table can be associated with many other tables and vice versa
43
Describe the many-to-many entity relationship
when one or more items in one table can have a relationship to one or more items in another table and vice versa
44
What do we mean by normalisation?
the process of coming up with the best possible layout for a relational database
45
What are some things normalisation does?
-remove unnecessary duplicates
-consistent data throughout linked tables
-records can be added and removed without issues
-complex queries can be carried out
46
What are the types of normalisation?
-1NF (1st normal form)
-2NF (2nd normal form)
-3NF (3rd normal form)
47
What does 1NF do?
makes sure there's no attribute that contains more than a single value
48
What does 2NF do?
makes sure that the relational database:
-hasno partial dependencies
-is in 1NF
49
What does 3NF do?
makes sure the relational database:
-is in 2NF
-contains no non-key dependencies (attributes which depend of value of primary key only)
50
What is indexing?
a method used to store the position of each record when ordered by a certain attribute
51
What is indexing used for?
to look up and access data from the database quickly
52
What is something to remember when indexing records?
the primary key is automatically indexed
53
How is data entered into databases?
-manually entered
-scanned
54
What is SQL?
a declarative language used to manipulate databases
- stands for structured query language
55
What are all the SQL commands? (9)
SELECT
FROM
WHERE
ORDER BY
JOIN
DELETE
INSERT INTO
DROP
CREATE
56
What do the SELECT, FROM, WHERE commands do?
SELECT- collects fields from a given table
FROM- specifies which table/tables the info will come from
WHERE- specifies the search criteria
57
What does the ORDER BY command do?
specifies whether you want data to be in ascending or descending order
58
What does the JOIN command do?
provides a method of combining rows from multiple tables based on a common field between them
59
What does the CREATE command do?
allows you to make new databases
60
What does the DELETE command do?
deletes a record from a table
61
What does the INSERT INTO command do?
inserts a new record in a table
62
What does the DROP command do?
removes a whole database/table
63
What do we mean by referential integrity?
the process ensuring consistency
- makes sure that info isn't removed if required elsewhere in a linked system
64
What is a transaction?
a single operation executed on data
65
What is ACID and what does it stand for?
properties required by all database transactions
-atomicity
-consistency
-isolation
-durability
66
What is atomicity?
when a transaction must be processed in its entirety or not at all
67
What is consistency?
when a transaction must keep the referential integrity rules between linked tables
68
What is isolation?
simultaneous execution of transactions must lead to the same result as if they were executed one after the other
69
What is durability?
when a transaction has been executed it will remain so
70
What is record locking?
the process of preventing simultaneous access of records in a database
71
What is record locking used for?
to prevent inconsistencies or loss of updates
72
What is the problem with record locking?
deadlock- where processes have effectively locked themselves out because they are all waiting on each other to do something
73
What is redundancy?
the process of having one or more copies of data in physically different locations
- means if there is any damage to one copy, others can be recovered
74
What is a network?
two or more computers connected together that can transmit data
- allows computers on opposite sides of the globe to communicate with each other
75
What are some positives of networks?
-users can share files
-communication with other people
-users can access files from any computer on the network
76
What are some downsides of networks?
-increased security risks to data
-malware and viruses spread easily between computers
-if the server fails, the computer connected to it may not work
-computers may run slower if there is a lot of data travelling on the network
77
What are protocols?
set of rules defining how two devices communicate with each other
78
What is the TCP/IP stack?
transmission control protocol/internet protocol
-stack of networking protocols that work together passing packets during communication
79
What are the protocol layers?
-application
-transport
-network
-link
80
Describe the application layer. What protocols are used during this?
specifies which protocols need to be used in order to relate the application that's being sent
protocols: FTP, HTTP, HTTPS, SMTPP, IMAP
81
Describe the transport layer. What protocols are used during this?
-sets up communication between two hosts
-splits data into packets
-requests transmission of any lost packets
protocols: TCP, UDP
82
Describe the network layer. What protocols are used during this?
-addresses and packages data for transmission
-router forwards packets across the network
protocol: IP
83
Describe the link layer
-the connection between network devices
-adds the MAC address identifying the Network Interface Cards of the source and destination computers
84
What happens with the TCP/IP stack on the recipients computer?
the layers occur again in reverse:
-link- removes the MAC addresses
-network- removes the IP addresses
-transport- removes the port number and reassembles the packets
-application- presents the data to the recipient in the form it was sent
85
How can we remember all the layers of the TCP/IP stack?
Always Think In Layers (ATIL)
86
What is LAN? What hardware does it need to become connected?
local area network
-a network that is spread over a small geographical area
- UTP cable
- fibre optic
- wi-fi
87
What is a WAN? What hardware does it need to become connected?
wide area network
-a network that is spread over a large geographical area (multiple LAN in different areas which are connected)
- telephone lines
-fibre optic cables
-satellite links
88
What is DNS?
domain name system
-method of naming internet resources
-translates domain names into IP addresses when we access a website
89
How does the DNS translate the domain name into the IP address when a user enters a website name? (6)
-client enters URL into browser
-browser checks local cache
-URL passed to DNS recursive resolver, checks cache
-URL passed to the root name server (contains address of the .com server)
-URL passed to the top level domain server (contains address of all sites register under .com)
-URL passed to the authoritative server (server of the actual requested device
90
What happens when the DNS cant find the IP address of the website URL?
outputs an error message (e.g. error code: 404, website address not found)
91
What is circuit switching?
a method of communication where a direct link is created between two devices
- Link maintained for the entire conversation
- The two devices must transfer and receive data at the same rate
92
What are some +/- of circuit switching? (2, 3)
+the data arrives in a logical order which results in a quicker reconstruction of the data
+enables two uses to hold a call without delay in speech
-bandwidth is wasted during periods of time where no data is sent
-the devices must transfer and receive data at the same rate
-since switches are used, electrical interference is produced which can corrupt or lose data
93
What is packet switching?
a method of communicating packets of data across a network
- a packet is just a section of the data
- packets aren’t limited to a single route
94
What are some +/- of packet switching? (3, 1)
+there are multiple methods to ensure data arrives
+there is more than one method of getting to the other devices, so if one path breaks you can use another
+you can transfer packets over very large networks to allow communication globally
-time is spent deconstructing and reconstructing the data packets
95
What are data packets?
-segments of data
-contain various pieces of information
96
What are topologies?
arrangement of elements in a computer network
97
What are the two types of topologies? What do they represent?
logical: the way in data flows around a network
physical: the physical layout of the network
98
Name the three topologies
-bus
-star
-mesh
99
Draw diagrams showing the three topologies
bus topology: data:image/png;base64,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
star topology: https://circuitglobe.com/wp-content/uploads/2019/06/star-topology.jpg
mesh topology: 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
100
What does a bus topology do?
all the terminals (devices) are connected to a backbone cable
101
What are some +/- when using the bus topology? (1, 3)
+cheaper to set up, doesn’t require any
additional hardware
-if backbone cable fails, the entire network
gets disconnected
-as traffic increases, performance
decreases
-all computers can see the data
transmission
102
What does a star topology do?
uses a central node (switch/computer) to direct the flow of data,
MAC (Media Access Control) addresses identify each device
103
What are some +/- when using the star topology? (5, 2)
+performance is consistent even if network
is being heavily used
+if one cable fails, only that station is
affected
+transmits data faster, so it gives better
performance than bus topology
+ easy to add new stations
+no data collisions
-expensive due to switch and cabling
-if the central switch fails, the rest of the
network fails
104
What does a mesh topology do?
where every node is connected to every other node
105
What are some +/- when using the mesh topology? (4, 2)
+no cabling cost
+as nodes increase, the reliability and speed of network becomes better
+nodes automatically get incorporated
+it’s faster since nodes don’t go through a central switch
-you have to purchase devices with
wireless capabilities
-maintaining the network is difficult
106
What are firewalls? How do they work?
software/devices designed to prevent unauthorised access to a network
- consist of two network interface cards (NICs), in-between the user and their internet connection
- pass packets between these two NICs and compares them against a set of rules (packet filters) set by the firewall software
- perform packet filtering / static filtering
- limit network access in accordance with administrator rules and
policies
107
What is a proxy server?
an intermediary, collecting and sending the data on behalf of the user
108
What do proxy servers do?
-protect the privacy of the user who remains anonymous
-cache frequently used website data making it faster to load
-reduce the web traffic
- prevent access to sensitive or irrelevant information at work or at school
109
What are the different types of network hardware? (8)
-modem
-router
-cable
-NICs
-WAP
-hub
-switch
-gateways
110
What do NICs do?
network interface cards
-assigns a unique MAC address to each device
111
What do switches do?
directs flow of data across a network
-connects everything
112
What do WAPs do?
wireless access point
-allows devices to connect to a network wirelessly
113
What do routers do?
used to connect two or more networks together
114
What do gateways do?
used when protocols aren't the same between networks
- translates protocols so that both networks have the same
115
What are client-server networks?
terminals known as clients, connected to a server
- a server is just a powerful central computer, holds all important info, has extra processing power and, clients can request to use it
116
What are +/- of using client-server networks? (3, 2)
+more secure
+central backups eliminate the need for client backups
+sharing data between resources and clients
-expensive to set up
-staff with training are required to maintain the server
117
What are peer-to-peer networks?
computers connected to each other so that they can share files
118
What are some positives when using peer-to-peer networks?
+inexpensive to set up
+allows users to share resources
+easy to maintain
119
What is HTML used for?
language that web pages are written in
-allows a browser to interpret and render a webpage for the viewer by describing the structure and order of the webpage
120
What are all the HTML tags needed to know? (13)