Hash functions MCQs

By: Prof. Dr. Fazal Rehman Shamil | Last updated: September 20, 2024

What is a hash function?
A) A function that transforms input data into a fixed-size string of characters
B) A function that sorts data
C) A function that retrieves data from a database
D) A function that encrypts data
Answer: A) A function that transforms input data into a fixed-size string of characters

Which of the following is a key property of a good hash function?
A) It must be easy to compute
B) It should produce unique outputs for all inputs
C) It must be reversible
D) It should produce outputs in a sorted order
Answer: A) It must be easy to compute

What is the purpose of using a hash function in data structures?
A) To store data in a sorted manner
B) To create a unique identifier for each data element
C) To map data to a specific memory location for efficient retrieval
D) To encrypt sensitive information
Answer: C) To map data to a specific memory location for efficient retrieval

What is a common problem associated with hash functions?
A) Data redundancy
B) Collisions
C) Memory overflow
D) Slow computation
Answer: B) Collisions

Which type of hash function uses a mathematical operation to determine the index?
A) Cryptographic hash function
B) Multiplicative hash function
C) Perfect hash function
D) Non-cryptographic hash function
Answer: D) Non-cryptographic hash function

What is the primary goal of a cryptographic hash function?
A) To ensure fast data retrieval
B) To provide data integrity and security
C) To reduce memory usage
D) To simplify data processing
Answer: B) To provide data integrity and security

In a hash function, what does the term “collision” refer to?
A) When two different inputs produce the same output
B) When a hash function fails to compute
C) When the output exceeds the maximum size
D) When inputs are processed too slowly
Answer: A) When two different inputs produce the same output

Which of the following is an example of a cryptographic hash function?
A) SHA-256
B) Division method
C) Multiplicative hashing
D) Linear probing
Answer: A) SHA-256

What is the role of a seed in a hash function?
A) To initialize the hash process
B) To ensure uniform distribution of outputs
C) To prevent collisions
D) To enhance security
Answer: A) To initialize the hash process

Which hashing technique is likely to lead to clustering?
A) Division method
B) Chaining
C) Linear probing
D) Double hashing
Answer: C) Linear probing

What is a perfect hash function?
A) A hash function that minimizes memory usage
B) A hash function that produces no collisions
C) A hash function that sorts data
D) A hash function that is difficult to compute
Answer: B) A hash function that produces no collisions

What is the main disadvantage of using cryptographic hash functions in a hash table?
A) They are slower to compute than non-cryptographic functions
B) They require more memory
C) They are prone to collisions
D) They produce variable output sizes
Answer: A) They are slower to compute than non-cryptographic functions

Which of the following techniques can reduce collisions in hash tables?
A) Using a poor hash function
B) Increasing the size of the hash table
C) Reducing the number of elements
D) Both B and C
Answer: D) Both B and C

What is the result of applying a hash function to a data set?
A) A sorted list
B) A fixed-length output
C) A random output
D) A complex data structure
Answer: B) A fixed-length output

What is the purpose of the modulus operator in hash functions?
A) To encrypt the data
B) To ensure the output fits within the size of the hash table
C) To sort the data
D) To generate random numbers
Answer: B) To ensure the output fits within the size of the hash table

Which of the following is NOT a characteristic of a good hash function?
A) Deterministic
B) Fast computation
C) Uniqueness of output
D) Reversible
Answer: D) Reversible

How can you improve a hash function’s performance?
A) Increase the size of the input data
B) Use a better hash algorithm
C) Minimize the number of collisions
D) Both B and C
Answer: D) Both B and C

What is the significance of the avalanche effect in hash functions?
A) Small changes in input produce significant changes in output
B) The output remains constant despite changes in input
C) Outputs are predictable based on inputs
D) It minimizes collisions
Answer: A) Small changes in input produce significant changes in output

What is a hashing algorithm?
A) A function that encrypts data
B) A method for calculating a hash value
C) A process for sorting data
D) A technique for compressing data
Answer: B) A method for calculating a hash value

What is the main benefit of using a hash function in a database?
A) Faster search and retrieval of data
B) Easier data management
C) Simplified user interface
D) Enhanced data security
Answer: A) Faster search and retrieval of data

What does “hashing” refer to in computer science?
A) Encrypting data
B) Converting data into a fixed-length string
C) Compressing data
D) Sorting data
Answer: B) Converting data into a fixed-length string

Which hash function is best for ensuring data integrity?
A) Cryptographic hash function
B) Non-cryptographic hash function
C) Perfect hash function
D) Universal hash function
Answer: A) Cryptographic hash function

What is the significance of the output size in a hash function?
A) It determines the security level
B) It affects the speed of computation
C) It limits the input data size
D) It has no significance
Answer: A) It determines the security level

Which hash function is designed to be irreversible?
A) Division hashing
B) SHA-1
C) Multiplicative hashing
D) Linear hashing
Answer: B) SHA-1

What is a universal hash function?
A) A hash function designed to work for all types of data
B) A hash function that minimizes the chance of collision
C) A hash function that can be used for both encryption and hashing
D) A hash function with a fixed output size
Answer: B) A hash function that minimizes the chance of collision

What is a common application of hash functions in security?
A) Data storage
B) Digital signatures
C) File compression
D) Data retrieval
Answer: B) Digital signatures

In a hash table, which operation can be directly impacted by a poorly designed hash function?
A) Sorting
B) Searching
C) Data retrieval
D) Both B and C
Answer: D) Both B and C

Which of the following statements about hash functions is TRUE?
A) They should always produce unique outputs
B) They can be used to encrypt data
C) They should be deterministic
D) They can only be used in hash tables
Answer: C) They should be deterministic

What is the output of a hash function known as?
A) Hash code
B) Hash value
C) Hash index
D) Hash key
Answer: B) Hash value

Which hash function is primarily used in Bitcoin?
A) MD5
B) SHA-256
C) SHA-1
D) HMAC
Answer: B) SHA-256

What is the primary challenge when designing a hash function?
A) Ensuring it is easy to compute
B) Preventing collisions
C) Making it reversible
D) Ensuring it uses minimal memory
Answer: B) Preventing collisions

What type of data can be used as input for a hash function?
A) Only numeric data
B) Only string data
C) Any type of data
D) Only structured data
Answer: C) Any type of data

Which of the following is a common use case for non-cryptographic hash functions?
A) Data integrity verification
B) Password hashing
C) Data indexing in hash tables
D) Digital signatures
Answer: C) Data indexing in hash tables

How does a hash function contribute to the efficiency of data retrieval?
A) By sorting the data
B) By reducing the number of comparisons needed
C) By encrypting the data
D) By compressing the data
Answer: B) By reducing the number of comparisons needed