Database Administrator Certification Exam
Questions and Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. Which of the following is a key responsibility of a database
administrator?
A. Writing application code
B. Designing network protocols
C. Managing database security and access controls
D. Developing user interfaces
Rationale: The primary role of a DBA is to manage, secure, and
maintain databases, including user access and permissions.
Application code development or network protocols fall outside
typical DBA responsibilities.
2. What does ACID stand for in database systems?
A. Atomicity, Consistency, Isolation, Durability
B. Accuracy, Consistency, Integration, Dependability
, C. Atomicity, Consistency, Isolation, Durability
D. Availability, Consistency, Integrity, Data
Rationale: ACID properties ensure reliable transaction processing.
Atomicity ensures all parts of a transaction succeed or fail together;
Consistency ensures database rules are not violated; Isolation keeps
concurrent transactions independent; Durability guarantees
committed transactions persist.
3. Which SQL command is used to remove a table from the
database?
A. REMOVE TABLE
B. DELETE TABLE
C. DROP TABLE
D. TRUNCATE TABLE
Rationale: DROP TABLE permanently removes a table and all its data.
TRUNCATE TABLE removes data but keeps the table structure.
4. What type of index stores pointers to data in a sorted order to
improve query performance?
A. Hash index
, B. B-tree index
C. Bitmap index
D. Full-text index
Rationale: B-tree indexes maintain a balanced tree structure, enabling
efficient searching, insertion, and deletion operations for ordered
data.
5. Which database backup type includes all changes since the last full
backup?
A. Differential backup
B. Incremental backup
C. Full backup
D. Snapshot backup
Rationale: Incremental backups capture only data changes since the
last backup (full or incremental), making them faster and smaller than
full backups.
6. In SQL, which constraint ensures that a column cannot have NULL
values?
A. UNIQUE
, B. PRIMARY KEY
C. NOT NULL
D. CHECK
Rationale: NOT NULL explicitly prohibits NULL entries in a column,
ensuring that every row contains a valid value.
7. What is the primary purpose of database normalization?
A. Increase storage size
B. Reduce data redundancy and improve data integrity
C. Make queries faster in all cases
D. Ensure all tables have primary keys
Rationale: Normalization organizes data to minimize duplication and
maintain consistency, although sometimes it may require additional
joins which can affect query performance.
8. Which of the following SQL statements is used to modify existing
records in a table?
A. INSERT
B. CREATE
Questions and Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which of the following is a key responsibility of a database
administrator?
A. Writing application code
B. Designing network protocols
C. Managing database security and access controls
D. Developing user interfaces
Rationale: The primary role of a DBA is to manage, secure, and
maintain databases, including user access and permissions.
Application code development or network protocols fall outside
typical DBA responsibilities.
2. What does ACID stand for in database systems?
A. Atomicity, Consistency, Isolation, Durability
B. Accuracy, Consistency, Integration, Dependability
, C. Atomicity, Consistency, Isolation, Durability
D. Availability, Consistency, Integrity, Data
Rationale: ACID properties ensure reliable transaction processing.
Atomicity ensures all parts of a transaction succeed or fail together;
Consistency ensures database rules are not violated; Isolation keeps
concurrent transactions independent; Durability guarantees
committed transactions persist.
3. Which SQL command is used to remove a table from the
database?
A. REMOVE TABLE
B. DELETE TABLE
C. DROP TABLE
D. TRUNCATE TABLE
Rationale: DROP TABLE permanently removes a table and all its data.
TRUNCATE TABLE removes data but keeps the table structure.
4. What type of index stores pointers to data in a sorted order to
improve query performance?
A. Hash index
, B. B-tree index
C. Bitmap index
D. Full-text index
Rationale: B-tree indexes maintain a balanced tree structure, enabling
efficient searching, insertion, and deletion operations for ordered
data.
5. Which database backup type includes all changes since the last full
backup?
A. Differential backup
B. Incremental backup
C. Full backup
D. Snapshot backup
Rationale: Incremental backups capture only data changes since the
last backup (full or incremental), making them faster and smaller than
full backups.
6. In SQL, which constraint ensures that a column cannot have NULL
values?
A. UNIQUE
, B. PRIMARY KEY
C. NOT NULL
D. CHECK
Rationale: NOT NULL explicitly prohibits NULL entries in a column,
ensuring that every row contains a valid value.
7. What is the primary purpose of database normalization?
A. Increase storage size
B. Reduce data redundancy and improve data integrity
C. Make queries faster in all cases
D. Ensure all tables have primary keys
Rationale: Normalization organizes data to minimize duplication and
maintain consistency, although sometimes it may require additional
joins which can affect query performance.
8. Which of the following SQL statements is used to modify existing
records in a table?
A. INSERT
B. CREATE
