Q.1 What is a distributed database?
A single database stored on one computer
A database that stores data across multiple networked computers
A database without a DBMS
A database that uses only in-memory storage
Explanation - A distributed database stores data on multiple computers connected via a network, but it appears to users as a single database.
Correct answer is: A database that stores data across multiple networked computers
Q.2 Which of the following is NOT a type of distributed database?
Homogeneous distributed database
Heterogeneous distributed database
Centralized database
Federated database
Explanation - A centralized database stores all data in one location, unlike distributed databases.
Correct answer is: Centralized database
Q.3 What is data fragmentation in distributed databases?
Dividing the database into smaller pieces stored at different sites
Copying the entire database to every site
Deleting unused data
Encrypting database tables
Explanation - Fragmentation splits a database into fragments to store across sites for efficiency and reliability.
Correct answer is: Dividing the database into smaller pieces stored at different sites
Q.4 Which fragmentation type ensures that each fragment contains all columns of some rows?
Vertical fragmentation
Horizontal fragmentation
Mixed fragmentation
Replication
Explanation - Horizontal fragmentation divides tables by rows, so each fragment contains all columns but only some rows.
Correct answer is: Horizontal fragmentation
Q.5 Which fragmentation type divides tables by columns?
Horizontal fragmentation
Vertical fragmentation
Mixed fragmentation
None of the above
Explanation - Vertical fragmentation divides tables into subsets of columns, typically including the primary key to maintain integrity.
Correct answer is: Vertical fragmentation
Q.6 What is replication in distributed databases?
Dividing data into fragments
Copying data across multiple sites
Deleting old data
Merging two databases into one
Explanation - Replication improves reliability and performance by storing copies of data at multiple sites.
Correct answer is: Copying data across multiple sites
Q.7 Which of the following is a challenge in distributed databases?
Data consistency
Transaction management
Query optimization
All of the above
Explanation - Distributed databases must manage consistency, transactions, and optimize queries across multiple sites.
Correct answer is: All of the above
Q.8 What is a homogeneous distributed database?
Databases with different DBMS at different sites
Databases with the same DBMS at all sites
A database stored in a single location
A database that uses cloud storage only
Explanation - Homogeneous distributed databases use the same DBMS across all sites, making management and queries easier.
Correct answer is: Databases with the same DBMS at all sites
Q.9 What is a heterogeneous distributed database?
Databases with different DBMS at different sites
Databases with the same DBMS at all sites
A centralized database
A read-only database
Explanation - Heterogeneous distributed databases combine different types of DBMS, requiring additional integration and translation mechanisms.
Correct answer is: Databases with different DBMS at different sites
Q.10 Which of the following ensures atomicity in distributed transactions?
Two-phase commit protocol
Replication
Fragmentation
Query optimization
Explanation - The two-phase commit protocol ensures that a distributed transaction is either fully committed at all sites or fully rolled back.
Correct answer is: Two-phase commit protocol
Q.11 Which of the following improves query performance in distributed databases?
Fragmentation
Replication
Caching
All of the above
Explanation - Fragmentation, replication, and caching reduce access time and improve distributed query performance.
Correct answer is: All of the above
Q.12 Transparency that hides the complexity of distributed database locations is called:
Replication transparency
Location transparency
Fragmentation transparency
Transaction transparency
Explanation - Location transparency allows users to access data without knowing its physical location across sites.
Correct answer is: Location transparency
Q.13 Which type of transparency ensures users are unaware of multiple copies of data?
Replication transparency
Location transparency
Transaction transparency
Performance transparency
Explanation - Replication transparency hides the fact that data may be duplicated at multiple sites from users.
Correct answer is: Replication transparency
Q.14 Which protocol is commonly used to maintain consistency in replicated distributed databases?
Two-phase commit protocol
Three-phase commit protocol
Quorum-based protocol
Both two-phase commit and quorum-based protocols
Explanation - Consistency in replicated databases is maintained using protocols like two-phase commit or quorum-based approaches.
Correct answer is: Both two-phase commit and quorum-based protocols
Q.15 A federated database system is:
A distributed database with autonomous component databases
A database stored only in the cloud
A database that uses only vertical fragmentation
A database with no replication
Explanation - A federated database integrates autonomous databases to appear as a single system to users.
Correct answer is: A distributed database with autonomous component databases
Q.16 Which of the following is true about distributed transactions?
They occur entirely within a single site
They involve multiple sites
They do not require ACID properties
They cannot be rolled back
Explanation - Distributed transactions involve operations across multiple sites and must maintain ACID properties.
Correct answer is: They involve multiple sites
Q.17 Which is a disadvantage of distributed databases?
Improved reliability
Increased query performance
Complexity in management
Fault tolerance
Explanation - Distributed databases improve performance and reliability but add management complexity.
Correct answer is: Complexity in management
Q.18 What does concurrency control in distributed databases manage?
Multiple users accessing the database simultaneously
Data replication only
Fragmentation only
Backup processes
Explanation - Concurrency control ensures data consistency when multiple users perform operations simultaneously across sites.
Correct answer is: Multiple users accessing the database simultaneously
Q.19 Which of the following ensures that users see a consistent database state despite failures?
Replication
Transaction management
Concurrency control
Query optimization
Explanation - Transaction management guarantees ACID properties, maintaining consistency even in distributed environments.
Correct answer is: Transaction management
Q.20 Which of the following is a main design objective of distributed databases?
Transparency
Reliability
Performance
All of the above
Explanation - Distributed databases aim for transparency, reliability, and high performance.
Correct answer is: All of the above
Q.21 What is meant by fragmentation transparency?
Users cannot see that data is fragmented across sites
Data is encrypted across fragments
Users cannot update fragmented data
Data is replicated across all sites
Explanation - Fragmentation transparency hides the fact that a table is split into fragments across multiple sites.
Correct answer is: Users cannot see that data is fragmented across sites
Q.22 In distributed databases, what is meant by local autonomy?
Each site can function independently
The database cannot be accessed remotely
Data cannot be replicated
All sites must always commit simultaneously
Explanation - Local autonomy allows individual sites in a distributed database to operate independently for local transactions.
Correct answer is: Each site can function independently
Q.23 Which of the following is a common method to improve reliability in distributed databases?
Fragmentation
Replication
Using a single central server
Reducing queries
Explanation - Replication stores copies of data across multiple sites, ensuring availability in case of failures.
Correct answer is: Replication
Q.24 Distributed deadlock occurs when:
Two transactions wait indefinitely for resources across sites
A database is fragmented
Replication fails
A query takes too long
Explanation - Distributed deadlocks happen when transactions on different sites block each other in a cyclic wait situation.
Correct answer is: Two transactions wait indefinitely for resources across sites