Which of these data structures can provide a more secure and performant alternative to a hashmap when handling user authentication data, especially in scenarios prone to hash flooding attacks?
Queue
Linked list
Tree
Array
In a web server implemented using a hashmap to store cached web pages, which collision resolution strategy is generally preferred for its performance in handling a high volume of concurrent requests?
Double Hashing
Separate Chaining with balanced binary search trees
Open Addressing with linear probing
Separate Chaining with linked lists
Hopscotch hashing aims to improve the performance of open addressing by:
Using a dynamic array to resize the table when the load factor gets high.
Using multiple hash tables to store keys with different hash values.
Employing a binary search tree for efficient collision resolution.
Limiting the maximum distance a key can be placed from its original hash index.
What is the primary reason for using a prime number as the size of a hash table in many implementations?
To make the implementation of the hash table simpler.
To minimize the memory usage of the hash table.
To increase the speed of hash function computation.
To ensure an even distribution of keys across the hash table, reducing collisions.
Why is it generally recommended to avoid using mutable objects as keys in hash tables?
Mutable keys make the implementation of the hash table significantly more complex.
Using mutable keys increases the memory overhead of the hash table.
Mutable keys can lead to inconsistent state if their values are modified after being inserted into the hash table.
Hash tables cannot store mutable objects as keys; only immutable objects are allowed.
In the context of hashmaps, what is a 'universal hash function' primarily designed to protect against?
Denial-of-service attacks caused by hash flooding.
Collisions caused by malicious input specifically crafted to exploit a known hash function.
Data corruption caused by accidental hash collisions between legitimate inputs.
Attempts to guess the keys used in the hashmap by analyzing the distribution of hashed values.
Python dictionaries use open addressing for collision resolution. Which of the following techniques helps mitigate the performance degradation caused by clustering in open addressing?
Robin Hood Hashing
Using a cryptographic hash function
Linear Probing with a prime step size
Separate Chaining
Which of the following is NOT a valid mitigation strategy against hash flooding attacks?
Using a fixed-size hashmap to limit the maximum number of collisions.
Switching to a different data structure like a tree-based map that offers consistent performance.
Implementing a random salt value in the hash function to make collisions unpredictable.
Employing a bloom filter to quickly identify and discard potentially malicious input.
How can a hash flooding attack impact the performance of a web server using a hashmap to store session data?
It can cause a denial-of-service by forcing the server to handle a large number of collisions.
It can lead to increased memory usage and faster response times.
It can improve the efficiency of the hashmap by distributing data more evenly.
It has no impact on performance, as hash flooding attacks only target data integrity.
In the context of hash tables, what does a high load factor indicate?
A more efficient hash function is being used.
Lower memory usage.
A higher probability of collisions.
Faster insertion operations.