Corporate & IT Interview Preparation

Q.11 Medium Database/SQL

In cybersecurity, what does encryption primarily protect against?

A Physical theft of devices

B SQL injection attacks

C Unauthorized access to data during transmission

D Database schema changes

Correct Answer: C. Unauthorized access to data during transmission

Explanation:

Encryption converts data into unreadable format, protecting it from unauthorized access during transmission and storage.

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Q.12 Medium Database/SQL

Which sorting algorithm has the best average-case time complexity?

A Bubble Sort - O(n²)

B Merge Sort - O(n log n)

C Insertion Sort - O(n²)

D Selection Sort - O(n²)

Correct Answer: B. Merge Sort - O(n log n)

Explanation:

Merge Sort and Quick Sort have O(n log n) average complexity. Merge Sort guarantees this; Quick Sort can degrade to O(n²) in worst case.

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Q.13 Medium Database/SQL

What is the primary function of a query optimizer in a DBMS?

A Compile SQL queries into machine code

B Determine the most efficient execution plan for queries

C Encrypt sensitive data in queries

D Validate SQL syntax errors

Correct Answer: B. Determine the most efficient execution plan for queries

Explanation:

The query optimizer analyzes different execution strategies and selects the one with minimal resource consumption and execution time.

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Q.14 Medium Database/SQL

In machine learning basics, what is the purpose of training data in AI models?

A To test the final model accuracy

B To teach the model patterns and make predictions

C To validate model security

D To encrypt sensitive information

Correct Answer: B. To teach the model patterns and make predictions

Explanation:

Training data is used to teach AI models to recognize patterns. Test data evaluates accuracy; validation data prevents overfitting.

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Q.15 Hard Database/SQL

What is a deadlock in database management?

A A situation where transactions block indefinitely waiting for each other

B Loss of database connection

C Unauthorized access to database

D Corruption of data files

Correct Answer: A. A situation where transactions block indefinitely waiting for each other

Explanation:

A deadlock occurs when two or more transactions wait for resources held by each other, creating a circular wait condition that prevents progress.

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Q.16 Hard Database/SQL

Which of the following best describes eventual consistency in distributed databases?

A All nodes have identical data at all times

B Data will be consistent across all nodes eventually, not immediately

C Data consistency is never achieved

D Only primary nodes maintain consistency

Correct Answer: B. Data will be consistent across all nodes eventually, not immediately

Explanation:

Eventual consistency is a model in NoSQL and distributed systems where updates propagate asynchronously, achieving consistency over time rather than immediately.

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Q.17 Hard Database/SQL

In network protocols, which layer does TCP/IP operate at?

A Physical Layer

B Data Link Layer

C Transport and Network Layers

D Application Layer only

Correct Answer: C. Transport and Network Layers

Explanation:

TCP operates at Layer 4 (Transport) and IP at Layer 3 (Network) in the OSI model. Together they form the TCP/IP protocol suite.

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Q.18 Hard Database/SQL

What is the primary vulnerability addressed by SQL injection prevention techniques like parameterized queries?

A Buffer overflow attacks

B Injection of malicious SQL code into database queries

C Man-in-the-middle attacks

D DDoS attacks on database server

Correct Answer: B. Injection of malicious SQL code into database queries

Explanation:

Parameterized queries prevent SQL injection by separating query structure from data, ensuring user input cannot be interpreted as executable code.

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Q.19 Hard Database/SQL

In the context of graph databases, what is the primary advantage over relational databases for relationship-heavy queries?

A Lower storage requirements

B Faster execution of complex relationship traversals

C Better support for unstructured data

D Superior ACID compliance

Correct Answer: B. Faster execution of complex relationship traversals

Explanation:

Graph databases excel at querying relationships with O(1) traversal time, whereas relational databases require expensive JOIN operations for similar queries.

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Q.20 Easy Database/SQL

Which of the following is a non-relational database designed for handling unstructured data at scale?

A MongoDB

B PostgreSQL

C Oracle Database

D MySQL

Correct Answer: A. MongoDB

Explanation:

MongoDB is a NoSQL document database that handles unstructured and semi-structured data efficiently, unlike relational databases like PostgreSQL, Oracle, and MySQL.

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