WorksheetsH446_4_DB_Compression Quiz
Total questions: 79
Worksheet time: 40mins
What is the primary purpose of file compression?
To increase the file size
To reduce the storage space of files on disk
To enhance the quality of images
To slow down data transmission
What is the difference between lossy and lossless compression?
Lossy compression retains all information, lossless removes unnecessary information
Lossy compression removes non-essential information, lossless retains all information
Both remove all information
Both retain all information
Why is compression important for images on websites?
To make images look more colorful
To enable a web page to load quickly
To increase the file size
To reduce the number of images
What is a consequence of lossy compression on images?
Improved image quality
Increased file size
Displaying untidy and blocky compression artefacts
Slower data transmission
What type of compression is likely to be used for the following: a website image, a zipped file of long text documents and images, a PDF instruction manual?
Lossy compression
Lossless compression
Run Length Encoding
MP3 compression
What is the main advantage of lossless compression?
It reduces file size significantly
It maintains exact accuracy with no data loss
It is faster to process than lossy compression
It is used for audio files
What does Run Length Encoding (RLE) primarily record?
Every pixel in a sequence
The value and number of times a pixel repeats
Only the color of each pixel
The position of each pixel
In the context of the document, what is a common use of MP3 files?
Storing high-quality images
Compressing video files
Reducing audio file size
Encoding text documents
What is the main advantage of dictionary-based compression techniques?
It eliminates the need for encryption.
It reduces the size of the message significantly.
It increases the complexity of the message.
It requires more storage space.
In the context of encryption, what is the term for the original data or message?
Ciphertext
Key
Plaintext
Algorithm
What is a key in the context of encryption?
The original message
The encrypted message
The method used to encrypt data
The secret information used to lock or unlock the message
What type of cipher is the Caesar cipher?
Transposition cipher
Substitution cipher
Vernam cipher
Block cipher
How does the Caesar cipher work?
By reversing the order of letters
By shifting the letters of the alphabet by a given number of characters
By replacing each letter with a number
By using a complex mathematical algorithm
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Using the list above, what is the ciphertext for 'JULIUS CAESAR' using a shift of 5?
OZNQZX HFJXFW
KXQKXU FBDTFS
MZQMYV GCEUGT
PZORAY IGKYGX
What word can be translated from the following ciphertext using a key of -2: ZYBECP?
APPLE
ORANGE
BANANA
CHERRY
What is the Vernam cipher known for?
Being the first cipher invented
Being unbreakable
Being the simplest cipher
Being the most complex cipher
What is a one-time pad?
A type of paper used for encryption
A key that is shorter than the plaintext
An encryption key that is random and used only once
A method of decrypting messages
Using the ASCII chart and the XOR operator, what ciphertext character will be produced from the letter E with the key w?
A
Z
W
K
What is the main advantage of using symmetric (private key) encryption?
A) It uses two separate keys for encryption and decryption.
B) The same key is used for both encryption and decryption. Fast and easy to operate
C) It is impossible to intercept the key.
D) It does not require key exchange.
Why is a truly random sequence important in cryptanalysis and perfect security?
A) It can be easily predicted.
B) It ensures the key is mathematically impossible to break.
C) It is generated by a computer.
D) It is always the same for every encryption.
What is a potential risk of asymmetric (public key) encryption?
A) The public key is kept secret.
B) The private key can be easily deduced from the public key.
C) A message can be encrypted by a malicious third party.
D) It does not require digital signatures.
What is the primary purpose of a hashing function?
To encrypt data for secure transmission
To map an arbitrary length input to a fixed length output
To compress data for storage efficiency
To generate random numbers for cryptographic use
What is a hash total also referred to as?
Checksum or digest
Encryption key
Digital signature
Public key
What is the role of a digital signature in message security?
To encrypt the entire message
To verify the sender's identity and ensure message integrity
To compress the message for faster transmission
To generate a checksum for the message
What is a digital certificate used for?
To verify the trustworthiness of a message sender or website
To encrypt data for secure transmission
To store large amounts of data
To compress files for easier storage
Which infrastructure does a digital certificate allow the holder to use?
Public Key Infrastructure (PKI)
Transport Layer Security (TLS)
Secure Sockets Layer (SSL)
File Transfer Protocol (FTP)
What is the purpose of a digital signature in a digital certificate?
To authenticate the certificate as real
To encrypt the message content
To compress the data
To store the certificate's serial number
What is the difference between lossy and lossless data compression?
Lossy compression reduces file size by removing some data, while lossless compression retains all data
Lossy compression retains all data, while lossless compression removes some data
Both lossy and lossless compression remove data
Both lossy and lossless compression retain all data
What is an example of a pattern substitution compression algorithm?
Run-length encoding (RLE)
Huffman coding
Lempel-Ziv-Welch (LZW)
Arithmetic coding
What is one disadvantage of lossless compression methods for images?
They do not reduce file size as much as lossy methods
They reduce image quality
They are more complex to implement
They are not suitable for text files
What is meant by symmetric encryption?
The same key is used for both encryption and decryption
Different keys are used for encryption and decryption
It uses a public key for encryption
It uses a private key for decryption
Why is asymmetric encryption considered more secure than symmetric encryption?
It uses different keys for encryption and decryption
It uses the same key for both encryption and decryption
It is faster to implement
It requires less computational power
What is an entity in the context of database concepts?
A type of database
A category of object, person, event, or thing of interest
A programming language
A type of data storage device
Which of the following is an example of an entity in a database system for Human Resource Management?
Hard drive
Operating system
Employee
Software application
What is a flat file database?
A database with multiple tables
A database consisting of a single file
A database with complex relationships
A database stored in the cloud
Which attribute might be included for the entity 'Dentist'?
Genre
Qualification
Release Date
Manufacturer
What is the primary key in the entity description for a Dentist?
Title
DentistID
Surname
Qualification
Which of the following is an example of a one-to-one relationship?
Mother and Child
Customer and Order
Husband and Wife
Student and Course
What is a secondary key used for in a database?
To uniquely identify an entity
To maintain an index of primary keys
To quickly search the database
To create a new database
Which relationship type is represented by the connection between a Customer and a Product in an Order Processing database?
One-to-one
One-to-many
Many-to-many
None of the above
What is a foreign key in a relational database?
A unique identifier for each record in a table
An attribute that creates a join between two tables
A field that stores large amounts of text
A key that is used to encrypt data
In a one-to-many relationship between Dentist and Patient, which attribute acts as the foreign key?
Dentist(dentistID, dentistName)
Patient(patientID, patientName, dentistID)
PatientID
DentistID
Address
Qualification
What is required to link tables in a many-to-many relationship?
A single foreign key
A composite key
An extra table
A unique identifier
What is a composite primary key?
A key that consists of a single attribute
A key that consists of more than one attribute
A key that is used to encrypt data
A key that is used to link two tables
What is the purpose of drawing an entity relationship diagram in a database system?
To show all the relationships between different entities
To create a visual representation of data flow
To design the user interface of a database
To manage database security settings
In the example of a hospital inpatient system, which entities are involved?
Ward, Nurse, Patient, Consultant
Doctor, Patient, Medicine, Room
Hospital, Staff, Equipment, Visitor
Nurse, Doctor, Room, Equipment
What is referential integrity in a relational database?
Ensuring a component is not deleted if it is used in a product
Creating a backup of the database regularly
Designing the database schema
Optimizing database queries for speed
What type of relationship is shown in the screenshot for enforcing referential integrity?
One-to-Many
Many-to-Many
One-to-One
Many-to-One
What is a suitable primary key for the Property table?
Address
PropertyID
OwnerName
AskingPrice
Which of the following could be a secondary key in the Property table?
Number of Bedrooms
PropertyID
OwnerName
AskingPrice
What is the name given to a key that is made up of multiple attributes?
Primary Key
Composite Key
Foreign Key
Unique Key
What is meant by a foreign key?
A key that uniquely identifies each record in a table
A key that is used to encrypt data
A key that links two tables together
A key that is used to sort data
What is an identifier for the entity ExamPaper?
CourseID
ExamPaperID
DateOfExam
CandidateNumber
In a relational database, what is a primary key?
A key that uniquely identifies each record
A key that links two tables together
A key that is used for encryption
A key that is used to sort data
What is the use of a primary key as a foreign key?
To uniquely identify records in a single table
To link records between two tables
To encrypt data in a database
To sort data in ascending order
State an identifier for the entity ExamPaper.
ExamPaperID
CourseID
CandidateNumber
Subject
What is a primary key?
A unique identifier for a record
A duplicate entry in a table
A foreign key in another table
A non-unique identifier for a record
Explain the use of a primary key as a foreign key.
To establish a relationship between two tables
To duplicate data across tables
To delete records in a table
To create a new table
What is a relational database?
A collection of tables with relationships modeled by shared attributes
A single table with no relationships
A database with no attributes
A collection of unrelated data
What is the purpose of a primary key in a relational database?
To uniquely identify a record in a table
To store large amounts of data
To create a backup of the database
To encrypt the data
What is an index in the context of databases?
A mechanism to quickly locate a record with a particular primary key
A list of all tables in the database
A summary of the database content
A tool for encrypting data
Which TWO of the following are examples of entity name in a database table?
Book
DeweyCode
Title
Author
What is the purpose of normalisation in relational databases?
To increase data redundancy
To ensure data is unnecessarily duplicated
To split tables to get the best possible design for a relational database
To make data retrieval slower
What is a foreign key in the context of linking database tables?
A unique identifier for each record in a table
An attribute that links tables through a common attribute
A key that is not used in relational databases
A primary key in the first table
Which of the following is NOT a basic stage of normalisation?
First normal form
Second normal form
Fourth normal form
Third normal form
What condition must be met for a table to be in first normal form (1NF)?
It must contain repeating attributes
It must not have a primary key
It must contain no repeating attribute or groups of attributes
It must have a foreign key
What is the first stage in normalization when dealing with repeating groups of attributes in a table?
Combining all attributes into one table
Splitting the data into two tables
Removing all attributes
Adding more attributes
In a relational database, what is a table commonly referred to as?
Record
Attribute
Relation or Entity
Component
What is the relationship between the two entities, Product and Component?
(A product is assembled using multiple components, like a computer is made up of many different hardware devices)
Product is a type of Component
Product has Component
Component has Product
Product and Component are unrelated
Why is it not a good idea to allow space for four components in the record for each product?
It simplifies the database structure
It allows for more flexibility
It contains repeating attributes, which are not allowed in first normal form
It reduces the number of tables needed
What is the purpose of introducing a link table between Product and Component?
To reduce the number of components
To link the two tables and remove repeating attributes
To increase the number of attributes
To simplify the product table
Which normal form requires that a table contains no partial dependencies?
First normal form (1NF)
Second normal form (2NF)
Third normal form (3NF)
Fourth normal form (4NF)
In a many-to-many relationship, what is always needed between two entities?
A primary key
A foreign key
A link table
A composite key
In a many-to-many relationship, what is always needed between two entities?
A primary key
A foreign key
A junction table
A composite key
What does third normal form (3NF) ensure about attributes in a table?
All attributes are dependent on the primary key
All attributes are independent of the primary key
All attributes are dependent on non-key attributes
All attributes are independent of non-key attributes
Which table in the example provided contains a composite key?
Product
ProductComp
Component
Supplier
What is one of the main advantages of a normalised database over an un-normalised one?
Increased data redundancy
Easier data retrieval
Improved data integrity
Faster data entry
What is the purpose of normalising a database design?
To increase data redundancy
To remove redundant data
To make data entry faster
To complicate database structure
In the context of databases, what does data integrity mean?
Data is stored in multiple locations
Data is duplicated for safety
Data is consistent and accurate
Data is encrypted for security
