What is the size of an empty structure in C?

The correct answer is B: 1 byte. An empty structure in C has a size of 1 byte. This is to ensure each structure instance has a unique address in memory.

Which function is used to release dynamically allocated memory in C?

The correct answer is B: free(). The free() function deallocates memory that was previously allocated using malloc(), calloc(), or realloc(). delete() is used in C++.

What does 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), and Durability (permanent storage).

How is a two-dimensional array typically stored in memory in C?

The correct answer is C: Row-major order. C uses row-major order to store 2D arrays in memory. The elements are stored row by row sequentially in memory.

Which of the following is used to declare a constant in C?

The correct answer is B: const int x = 5;. In C, the 'const' keyword is used to declare constants. Once a const variable is initialized, its value cannot be changed. Options A, C, and D are not valid C syntax.

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Database/SQL

Programming, networking, database and OS questions

18 Q 2 Topics Take Mock Test

Difficulty: All Easy Medium Hard 11–18 of 18

Topics in Computer Knowledge

All C Programming 200 Database/SQL 100

Q.11 Hard Database/SQL

What does BASE model in NoSQL stand for?

A Basically Available, Soft state, Eventually consistent

B Batch Available, System Events, Eventual consistency

C Buffer Availability, Strong consistency, Event-driven

D Backup Availability, Security-first, Efficient

Correct Answer: A. Basically Available, Soft state, Eventually consistent

EXPLANATION

BASE is an alternative to ACID, prioritizing availability and partition tolerance. It accepts temporary inconsistencies that resolve eventually (eventual consistency).

Test

Q.12 Hard Database/SQL

In cybersecurity, what is a zero-day vulnerability?

A A security flaw unknown to vendors with no patch available

B A vulnerability found on the first day of software release

C A virus that activates at midnight

D A type of brute-force attack

Correct Answer: A. A security flaw unknown to vendors with no patch available

EXPLANATION

Zero-day vulnerabilities are previously unknown exploits with no patch. They're extremely dangerous because users have no defense until vendors develop and release fixes.

Test

Q.13 Hard Database/SQL

What does CAP theorem state in distributed systems?

A A system can guarantee at most 2 of 3: Consistency, Availability, Partition tolerance

B All distributed systems must be Consistent, Available, and Partition-tolerant

C Consistency requires Availability and Partitions

D Availability is always achieved in partitioned systems

Correct Answer: A. A system can guarantee at most 2 of 3: Consistency, Availability, Partition tolerance

EXPLANATION

CAP theorem (Brewer's theorem) states distributed systems must choose 2 of 3 properties: strong consistency (C), continuous availability (A), or tolerance to network partitions (P).

Test

Q.14 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.

Test

Q.15 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.

Test

Q.16 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.

Test

Q.17 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.

Test

Q.18 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.

Test

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