What does the acronym ACID stand for in database transactions?

The correct answer is A: Atomicity, Consistency, Isolation, Durability. ACID properties ensure reliable database transactions: Atomicity (all-or-nothing), Consistency (valid state), Isolation (concurrent independence), Durability (permanent storage).

What is the output of the expression: 10 / 3 * 3 in C?

The correct answer is B: 9. Division and multiplication have the same precedence and are evaluated left-to-right. Step 1: 10 / 3 = 3 (integer division). Step 2: 3 * 3 = 9. Therefore, the result is 9.

What is the primary advantage of using GraphQL over traditional REST APIs in modern application architecture?

The correct answer is B: GraphQL allows clients to request only required data fields, reducing over-fetching. GraphQL's query language enables clients to specify exact data requirements, eliminating over-fetching and under-fetching issues common in REST.

Which of the following correctly uses the ternary operator?

The correct answer is B: x = (a > b) ? a : b;. The ternary operator syntax is: condition ? value_if_true : value_if_false. Option B is the only correctly formatted statement.

What does ACID compliance in databases ensure?

The correct answer is B: Atomicity, Consistency, Isolation, and Durability of transactions. ACID is a fundamental database property: Atomicity (all-or-nothing), Consistency (valid state), Isolation (concurrent independence), Durability (permanent after commit).

Corporate & IT Interview Preparation

Q.71 Easy Database/SQL

In SQL, which JOIN returns only matching records from both tables?

A INNER JOIN

B LEFT JOIN

C FULL OUTER JOIN

D CROSS JOIN

Correct Answer: A. INNER JOIN

Explanation:

INNER JOIN returns only rows with matching values in both tables. LEFT JOIN includes unmatched left table rows, FULL OUTER JOIN includes all rows, and CROSS JOIN produces Cartesian product.

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Q.72 Easy Database/SQL

What is the time complexity of searching in a balanced binary search tree?

A O(log n)

B O(n)

C O(n log n)

D O(1)

Correct Answer: A. O(log n)

Explanation:

Balanced BSTs (AVL, Red-Black) maintain O(log n) search time by keeping height logarithmic. Unbalanced trees degrade to O(n) in worst case.

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Q.73 Easy Database/SQL

In cloud computing, what does IaaS stand for?

A Infrastructure as a Service

B Integration as a Service

C Intelligent as a Service

D Internal as a Service

Correct Answer: A. Infrastructure as a Service

Explanation:

IaaS provides virtualized computing resources over the internet (AWS EC2, Azure VMs). PaaS and SaaS are higher-level abstractions.

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Q.74 Easy Database/SQL

In cybersecurity, what is the primary purpose of a firewall?

A Control incoming and outgoing network traffic based on rules

B Encrypt all data transmitted

C Detect viruses and malware

D Manage user authentication

Correct Answer: A. Control incoming and outgoing network traffic based on rules

Explanation:

Firewalls filter traffic based on security policies. While they provide protection, encryption is separate, antivirus is different, and authentication is handled by other systems.

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Q.75 Easy Database/SQL

Which of the following is a ACID property that ensures all or nothing transaction execution?

A Atomicity

B Consistency

C Isolation

D Durability

Correct Answer: A. Atomicity

Explanation:

Atomicity ensures that a transaction is treated as a single unit - either all operations complete or none do.

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Q.76 Easy Database/SQL

What is the primary advantage of using INNER JOIN over OUTER JOIN in SQL?

A It processes faster for small datasets

B It returns only matching records from both tables

C It uses less memory than OUTER JOIN

D It can handle NULL values better

Correct Answer: B. It returns only matching records from both tables

Explanation:

INNER JOIN returns only rows that have matching values in both tables, making queries more efficient for specific requirements.

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Q.77 Easy Database/SQL

In a relational database, what does normalization primarily aim to eliminate?

A NULL values

B Data redundancy and anomalies

C Foreign key constraints

D Index creation

Correct Answer: B. Data redundancy and anomalies

Explanation:

Normalization removes data redundancy and prevents update, insertion, and deletion anomalies through organized table structures.

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Q.78 Easy Database/SQL

Which algorithm has O(n log n) time complexity and is preferred for large datasets in modern databases?

A Bubble Sort

B Merge Sort

C Selection Sort

D Insertion Sort

Correct Answer: B. Merge Sort

Explanation:

Merge Sort maintains O(n log n) complexity in all cases and is stable, making it ideal for sorting large datasets.

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Q.79 Easy Database/SQL

What is the primary purpose of indexing in databases?

A To reduce storage space

B To speed up data retrieval operations

C To enforce data integrity

D To manage concurrent access

Correct Answer: B. To speed up data retrieval operations

Explanation:

Indexes create a faster lookup structure similar to a book's index, enabling rapid data retrieval without full table scans.

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Q.80 Easy Database/SQL

In the OSI model, which layer is responsible for routing and logical addressing?

A Physical Layer

B Data Link Layer

C Network Layer

D Transport Layer

Correct Answer: C. Network Layer

Explanation:

The Network Layer (Layer 3) handles routing, IP addressing, and logical path determination for data packets.

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