WGU D330 OBJECTIVE ASSESSMENT 2 LATEST 2026
ACTUAL EXAM| D330 DATA SYSTEMS
ADMINISTRATION OA EXAM WITH 250 REAL EXAM
QUESTIONS AND CORRECT VERIFIED ANSWERS/
ALREADY GRADED A+ (MOST RECENT!!)
1. Which two SGA structures are required in every Oracle
instance? (Choose two.)
A. Large pool
B. Shared pool
C. Database buffer cache
D. Java pool
Correct Answer: B and C
Rationale: The Shared Pool and Database Buffer Cache are
mandatory components of the System Global Area (SGA) in
every Oracle instance. The Shared Pool caches SQL statements
and data dictionary information, while the Database Buffer
Cache stores data blocks read from disk. The Large Pool and
Java Pool are optional and configured only when specific
features (like RMAN backups or Java stored procedures) are
needed .
1
,2. Which statement best describes the difference between an
Oracle instance and an Oracle database?
A. An instance consists of memory structures and background
processes; a database consists of physical files.
B. An instance is used only during database creation; the
database is used all the time.
C. An instance is started when demands are high; the database is
used continuously.
D. An instance is configured using a pfile; a database is
configured using an spfile.
Correct Answer: A
Rationale: The Oracle instance is composed of the System
Global Area (SGA) memory structures and the background
processes (like DBWn, LGWR, PMON, SMON). The database
consists of the physical files on disk: control files, data files, and
redo log files. An instance can exist without a database (e.g.,
during creation), and a database can exist without an active
instance (when shutdown). They are separate but interdependent
components .
3. Which background process guarantees that committed data
is saved even when changes have not yet been written to
data files?
2
,A. DBWn (Database Writer)
B. PMON (Process Monitor)
C. LGWR (Log Writer)
D. CKPT (Checkpoint)
Correct Answer: C
Rationale: The Log Writer (LGWR) process writes redo log
entries from the redo log buffer to the online redo log files.
When a user issues a COMMIT, LGWR immediately writes the
transaction's redo information to disk. Even if the database
crashes before DBWn writes the changed data blocks to the
data files, the committed changes can be recovered by
reapplying the redo logs during instance recovery. DBWn writes
data blocks asynchronously and does not respond directly to
COMMIT commands .
4. A user updates several rows in a table and issues a
COMMIT. What does the DBWn process do at this moment?
A. Writes the changed blocks to data files immediately.
B. Writes the changed blocks to redo log files.
C. Triggers a checkpoint, causing LGWR to write to redo logs.
D. Does nothing in response to the COMMIT.
Correct Answer: D
Rationale: The Database Writer (DBWn) process is not triggered
3
, by COMMIT commands. When a user commits a transaction, only
the Log Writer (LGWR) is involved to ensure redo is written to
disk. DBWn writes dirty buffers from the database buffer cache
to data files asynchronously based on checkpoint activity, not in
response to commit events. This architecture allows efficient batch
writing of data blocks while maintaining durability through redo
logs .
5. Which SGA component contains the parsed SQL code for
reuse by multiple sessions?
A. Database buffer cache
B. Dictionary cache
C. Library cache
D. Redo log buffer
Correct Answer: C
Rationale: The Library Cache, which resides within the Shared
Pool, stores shared SQL areas containing parsed SQL statements
and their execution plans. When a user executes a SQL
statement, Oracle checks the library cache first. If the same
statement is found and execution plans are still valid, Oracle
reuses the parsed code, avoiding expensive hard parsing. This
sharing improves performance and reduces memory consumption.
4
ACTUAL EXAM| D330 DATA SYSTEMS
ADMINISTRATION OA EXAM WITH 250 REAL EXAM
QUESTIONS AND CORRECT VERIFIED ANSWERS/
ALREADY GRADED A+ (MOST RECENT!!)
1. Which two SGA structures are required in every Oracle
instance? (Choose two.)
A. Large pool
B. Shared pool
C. Database buffer cache
D. Java pool
Correct Answer: B and C
Rationale: The Shared Pool and Database Buffer Cache are
mandatory components of the System Global Area (SGA) in
every Oracle instance. The Shared Pool caches SQL statements
and data dictionary information, while the Database Buffer
Cache stores data blocks read from disk. The Large Pool and
Java Pool are optional and configured only when specific
features (like RMAN backups or Java stored procedures) are
needed .
1
,2. Which statement best describes the difference between an
Oracle instance and an Oracle database?
A. An instance consists of memory structures and background
processes; a database consists of physical files.
B. An instance is used only during database creation; the
database is used all the time.
C. An instance is started when demands are high; the database is
used continuously.
D. An instance is configured using a pfile; a database is
configured using an spfile.
Correct Answer: A
Rationale: The Oracle instance is composed of the System
Global Area (SGA) memory structures and the background
processes (like DBWn, LGWR, PMON, SMON). The database
consists of the physical files on disk: control files, data files, and
redo log files. An instance can exist without a database (e.g.,
during creation), and a database can exist without an active
instance (when shutdown). They are separate but interdependent
components .
3. Which background process guarantees that committed data
is saved even when changes have not yet been written to
data files?
2
,A. DBWn (Database Writer)
B. PMON (Process Monitor)
C. LGWR (Log Writer)
D. CKPT (Checkpoint)
Correct Answer: C
Rationale: The Log Writer (LGWR) process writes redo log
entries from the redo log buffer to the online redo log files.
When a user issues a COMMIT, LGWR immediately writes the
transaction's redo information to disk. Even if the database
crashes before DBWn writes the changed data blocks to the
data files, the committed changes can be recovered by
reapplying the redo logs during instance recovery. DBWn writes
data blocks asynchronously and does not respond directly to
COMMIT commands .
4. A user updates several rows in a table and issues a
COMMIT. What does the DBWn process do at this moment?
A. Writes the changed blocks to data files immediately.
B. Writes the changed blocks to redo log files.
C. Triggers a checkpoint, causing LGWR to write to redo logs.
D. Does nothing in response to the COMMIT.
Correct Answer: D
Rationale: The Database Writer (DBWn) process is not triggered
3
, by COMMIT commands. When a user commits a transaction, only
the Log Writer (LGWR) is involved to ensure redo is written to
disk. DBWn writes dirty buffers from the database buffer cache
to data files asynchronously based on checkpoint activity, not in
response to commit events. This architecture allows efficient batch
writing of data blocks while maintaining durability through redo
logs .
5. Which SGA component contains the parsed SQL code for
reuse by multiple sessions?
A. Database buffer cache
B. Dictionary cache
C. Library cache
D. Redo log buffer
Correct Answer: C
Rationale: The Library Cache, which resides within the Shared
Pool, stores shared SQL areas containing parsed SQL statements
and their execution plans. When a user executes a SQL
statement, Oracle checks the library cache first. If the same
statement is found and execution plans are still valid, Oracle
reuses the parsed code, avoiding expensive hard parsing. This
sharing improves performance and reduces memory consumption.
4
