161. What is the purpose of Transparent Data Encryption (TDE) in databases?
- a) To encrypt data at rest without application changes
- b) To encrypt network traffic
- c) To hide database schema
- d) To compress encrypted data
Answer: A - TDE encrypts database files on disk while maintaining transparent access for authorized users.
162. What is multi-master replication?
- a) A configuration where multiple nodes can accept writes and propagate changes
- b) A backup strategy with multiple primary copies
- c) A type of distributed query processing
- d) A security model with multiple administrators
Answer: A - Multi-master systems (e.g., PostgreSQL BDR) allow writes to any node but require conflict resolution.
163. What is quantum database technology primarily exploring?
- a) Using qubits to perform parallel database operations
- b) Storing data in quantum particles
- c) Encrypting data with quantum algorithms
- d) A theoretical database model with no practical applications
Answer: A - Quantum databases leverage superposition and entanglement for potential exponential speedups in certain operations.
164. What is the purpose of the SQL ROW LEVEL SECURITY feature?
- a) To restrict row access based on user characteristics
- b) To encrypt individual rows
- c) To optimize row storage
- d) To validate row integrity
Answer: A - RLS implements fine-grained access control (e.g., "users see only their own records").
165. What is blockchain-based database immutability?
- a) The inability to alter historical records without detection
- b) A read-only database mode
- c) A backup preservation technique
- d) A type of database compression
Answer: A - Blockchain's cryptographic chaining makes past data tamper-evident (though some systems allow "soft" deletes).
166. What is the difference between synchronous and asynchronous replication?
- a) Synchronous waits for confirmation from replicas, asynchronous does not
- b) Synchronous is faster, asynchronous is slower
- c) Synchronous works only in clusters, asynchronous works anywhere
- d) There is no practical difference
Answer: A - Synchronous replication guarantees consistency but impacts latency; asynchronous prioritizes availability.
167. What is the purpose of the SQL MASKING feature?
- a) To dynamically obscure sensitive data from unauthorized users
- b) To hide database errors
- c) To optimize query execution
- d) To compress data
Answer: A - Dynamic Data Masking (DDM) shows partial data (e.g., "XXX-XX-1234" for SSNs) without altering stored values.
168. What is a quorum in distributed database systems?
- a) The minimum number of nodes required to perform an operation
- b) A voting mechanism for schema changes
- c) A type of database backup
- d) A security protocol
Answer: A - Quorum systems (e.g., (N/2)+1 nodes) balance consistency and availability during network partitions.
169. What is the purpose of the SQL ALWAYS ENCRYPTED feature?
- a) To encrypt sensitive data in transit and at rest, even from DBAs
- b) To enforce encryption on all columns
- c) To replace TDE
- d) To encrypt database logs
Answer: A - Always Encrypted uses client-side encryption with keys never exposed to the database server.
170. What is conflict-free replicated data type (CRDT)?
- a) A data structure that automatically resolves sync conflicts
- b) A type of encrypted data
- c) A database backup format
- d) A conflict detection algorithm
Answer: A - CRDTs guarantee eventual consistency through mathematical properties (used in distributed systems like Redis).
171. What is the purpose of the SQL AUDIT command?
- a) To track and log database activities for security monitoring
- b) To verify data integrity
- c) To optimize database performance
- d) To check storage utilization
Answer: A - Auditing creates records of who did what and when (critical for compliance).
172. What is active-active replication?
- a) A configuration where all replicas accept reads and writes
- b) A high-performance backup strategy
- c) A type of database clustering
- d) A load balancing technique
Answer: A - Active-active systems distribute workload but require conflict resolution mechanisms.
173. What is the purpose of the SQL FEDERATED engine?
- a) To query remote databases as if they were local tables
- b) To implement federal security standards
- c) To encrypt data in transit
- d) To create distributed backups
Answer: A - Federated tables (in MySQL) provide transparent access to remote data without replication.
174. What is homomorphic encryption in database contexts?
- a) Performing computations on encrypted data without decryption
- b> Encrypting similar data the same way
- c) A database compression technique
- d) A type of blockchain encryption
Answer: A - Homomorphic encryption enables privacy-preserving queries but has significant performance overhead.
175. What is the purpose of the SQL FIREWALL feature?
- a) To detect and block suspicious database access patterns
- b> To encrypt network traffic
- c) To prevent physical access to servers
- d) To filter query results
Answer: A - Database firewalls (e.g., in Azure SQL) analyze SQL statements to prevent injection attacks.
176. What is a blockchain oracle in database systems?
- a) A service that provides external data to smart contracts
- b> A type of database index
- c) A backup verification tool
- d) A query optimization technique
Answer: A - Oracles bridge blockchain databases with off-chain data sources (e.g., market prices).
177. What is the purpose of the SQL TDE (Transparent Data Encryption) feature?
- a) To encrypt database files at rest without application changes
- b> To encrypt data in transit
- c) To hide database schema
- d) To compress encrypted data
Answer: A - TDE protects against physical theft of storage media by encrypting data files and logs.
178. What is differential privacy in database contexts?
- a> Adding statistical noise to query results to prevent re-identification
- b> Encrypting differences between database versions
- c> A backup strategy
- d> A type of database partitioning
Answer: A - Differential privacy (used in Apple, Google) allows aggregate analysis while protecting individual privacy.
179. What is the purpose of the SQL LEDGER feature?
- a> To create tamper-evident, blockchain-like tables
- b> To track financial transactions
- c> To implement write-ahead logging
- d> To encrypt audit trails
Answer: A - Ledger tables (in SQL Server 2022+) provide cryptographic proof of data integrity.
180. What is a zero-knowledge proof in database security?
- a> Verifying data authenticity without revealing the data itself
- b> A type of unbreakable encryption
- c> A backup verification method
- d> A query optimization technique
Answer: A - ZKPs enable privacy-preserving authentication (e.g., proving age without revealing birthdate).