Central Govt Exam Preparation — SSC, UPSC, Bank, Railway

Q.51 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.52 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.53 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).

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Q.54 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.

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Q.55 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).

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Q.56 Hard Database/SQL

In database replication, what is the primary difference between synchronous and asynchronous replication?

A Synchronous is always faster

B Asynchronous waits for replica confirmation; Synchronous does not

C Synchronous waits for replica confirmation; Asynchronous does not

D Both have identical performance characteristics

Correct Answer: C. Synchronous waits for replica confirmation; Asynchronous does not

Explanation:

Synchronous replication waits for replicas to acknowledge writes (safer but slower), while asynchronous replication doesn't wait (faster but less safe).

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Q.57 Hard Database/SQL

Which of the following best describes a distributed transaction and its challenges in microservices architecture?

A Transactions that execute only on primary databases

B Transactions spanning multiple services requiring coordination and handling failures

C Transactions that cannot be executed in microservices

D Local transactions that never require coordination

Correct Answer: B. Transactions spanning multiple services requiring coordination and handling failures

Explanation:

Distributed transactions in microservices require mechanisms like Saga pattern or Two-Phase Commit to maintain consistency across services.

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Q.58 Hard Database/SQL

In cybersecurity, what is SQL injection and why is it a critical vulnerability in 2024?

A Injecting SQL commands to execute unauthorized database operations

B A performance optimization technique

C A method to improve database security

D An outdated vulnerability no longer relevant

Correct Answer: A. Injecting SQL commands to execute unauthorized database operations

Explanation:

SQL injection allows attackers to insert malicious SQL code through application inputs, remaining a critical OWASP Top 10 vulnerability despite awareness.

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Q.59 Hard Database/SQL

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

A GraphQL always provides better performance

B GraphQL allows clients to request only required data fields, reducing over-fetching

C GraphQL eliminates the need for databases

D REST APIs are completely replaced by GraphQL

Correct Answer: B. GraphQL allows clients to request only required data fields, reducing over-fetching

Explanation:

GraphQL's query language enables clients to specify exact data requirements, eliminating over-fetching and under-fetching issues common in REST.

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Q.60 Hard Database/SQL

In a B-tree of order m, what is the maximum number of keys that a non-root node can contain?

A m-1

B m

C 2m-1

D 2m

Correct Answer: C. 2m-1

Explanation:

A B-tree of order m can have at most 2m-1 keys in any node and minimum m-1 keys in non-root nodes.

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