WGU D330 – DATA SYSTEMS
ADMINISTRATION (OA) Actual Exam | Official
Exam – Complete Q&A with Rationales – Pass
Guaranteed - A+ Graded
Total Questions: 50 | Time: 90 min | Pass: 80%
TABLE OF CONTENTS
Section 1 | Database Architecture & Installation | Q1 – Q10
Section 2 | User Security & Access Control | Q11 – Q20
Section 3 | Backup, Recovery & High Availability | Q21 – Q30
Section 4 | Performance Tuning & Optimization | Q31 – Q40
Section 5 | Monitoring, Automation & Maintenance | Q41 – Q50
Instructions: Choose the single best answer. Pass: 40 in 90 minutes.
══════════════════════════════════════
SECTION 1: DATABASE ARCHITECTURE & INSTALLATION Q1 – Q10
══════════════════════════════════════
Question 1 of 50
A database administrator is installing a new SQL Server 2019 instance on a Windows
Server 2022 machine with 128 GB of RAM. During the installation, the DBA must decide
how to allocate memory between the operating system and the database engine. The
server will host only this single instance and no other major applications.
A. Reserve 8 GB for the OS and set the SQL Server max server memory to 120 GB
B. Reserve 20 GB for the OS and set the SQL Server max server memory to 108 GB ✓
CORRECT
C. Leave max server memory at the default unlimited setting and let SQL Server manage
everything
D. Reserve 4 GB for the OS and set the SQL Server max server memory to 124 GB
,Correct Answer: B
Rationale: Leaving adequate memory for the OS prevents paging and ensures Windows
can handle I/O operations and other background tasks without starving. Option A risks
OS instability under load, while option C allows SQL Server to consume everything and
potentially crash the host. A good rule of thumb is to reserve at least 4 GB for the OS
plus 1 GB for every 8–16 GB of RAM over 16 GB.
Question 2 of 50
A Linux administrator is preparing to install PostgreSQL 15 on a RHEL 9 server. The
organization requires that the database data directory, WAL files, and temporary
tablespace files reside on separate mount points for optimal I/O separation. The
administrator needs to identify the default location where PostgreSQL expects its
configuration files after a standard RPM installation.
A. /var/lib/pgsql/15/data/pg_hba.conf and postgresql.conf are stored in
/etc/postgresql/15/main/
B. /var/lib/pgsql/15/data/ contains postgresql.conf, pg_hba.conf, and pg_ident.conf by
default ✓ CORRECT
C. /opt/postgresql/15/conf/ is the standard RPM location for all configuration files
D. /usr/share/pgsql/15/ stores the active configuration files used by the running
instance
Correct Answer: B
Rationale: A standard PostgreSQL RPM installation places the data directory and
configuration files together under /var/lib/pgsql/15/data/. Option A describes the
Debian/Ubuntu path structure, not RHEL, and option C does not reflect the actual RPM
layout. Keeping configs in the data directory simplifies backup consistency since a base
backup captures both data and configuration state.
Question 3 of 50
,A company is migrating from a single MySQL 8.0 instance to a new architecture using
InnoDB Cluster for high availability. The DBA is reviewing the instance configuration and
notices that the innodb_buffer_pool_size is currently set to 2 GB on a server with 64 GB
of RAM. The database is approximately 45 GB in size and experiences heavy read
activity.
A. Increase the buffer pool to 48 GB to cache the majority of the working set
B. Increase the buffer pool to 32 GB to balance caching with OS and other process
needs
C. Increase the buffer pool to 48 GB, but no more than 75% of total system memory ✓
CORRECT
D. Leave the buffer pool at 2 GB and add read replicas instead
Correct Answer: C
Rationale: The InnoDB buffer pool should be large enough to cache the frequently
accessed portion of the dataset, but MySQL documentation recommends capping it
around 75% of total RAM to leave headroom for the OS, thread stacks, and other
buffers. Option A could cause swapping or OOM conditions, while option B might
under-utilize available memory for this read-heavy workload. In practice, monitoring
buffer pool hit rates after the change confirms whether the working set is adequately
cached.
Question 4 of 50
An Oracle DBA is configuring a new 19c database on an Exadata system. The storage
administrator has created ASM disk groups using both high-redundancy and
normal-redundancy policies. The DBA needs to place the database's critical SYSTEM
and SYSAUX tablespaces in a disk group that provides three-way mirroring to protect
against double disk failures.
A. Use the normal-redundancy disk group because it mirrors each extent twice
, B. Use the high-redundancy disk group because it provides three-way mirroring ✓
CORRECT
C. Use the external-redundancy disk group and rely on the storage array RAID for
protection
D. Use the flex-redundancy disk group because it automatically selects the best
protection level
Correct Answer: B
Rationale: ASM high redundancy creates three copies of each extent, ensuring data
survives even if two disks fail simultaneously. Option A describes normal redundancy,
which only provides two-way mirroring and cannot tolerate a double failure. Exadata
deployments often use high redundancy for critical metadata and application data
where downtime is unacceptable.
Question 5 of 50
A database team is deploying MongoDB 6.0 as a replica set for a new application.
During the architecture review, the lead DBA emphasizes that the oplog size must be
carefully chosen because it directly impacts how long a secondary can be offline before
requiring a full resync. The production environment expects sustained write throughput
of approximately 2 GB per hour.
A. Set the oplog to 16 GB, which provides roughly 8 hours of write coverage
B. Set the oplog to 24 GB, which provides roughly 12 hours of write coverage ✓
CORRECT
C. Set the oplog to the default 5% of free disk space regardless of write volume
D. Set the oplog to 4 GB because larger oplogs slow down replication on secondaries
Correct Answer: B
Rationale: The oplog must be large enough to retain all operations during the maximum
expected secondary downtime or maintenance window. Option C ignores the actual
write rate and could result in an oplog too small for recovery scenarios. MongoDB
ADMINISTRATION (OA) Actual Exam | Official
Exam – Complete Q&A with Rationales – Pass
Guaranteed - A+ Graded
Total Questions: 50 | Time: 90 min | Pass: 80%
TABLE OF CONTENTS
Section 1 | Database Architecture & Installation | Q1 – Q10
Section 2 | User Security & Access Control | Q11 – Q20
Section 3 | Backup, Recovery & High Availability | Q21 – Q30
Section 4 | Performance Tuning & Optimization | Q31 – Q40
Section 5 | Monitoring, Automation & Maintenance | Q41 – Q50
Instructions: Choose the single best answer. Pass: 40 in 90 minutes.
══════════════════════════════════════
SECTION 1: DATABASE ARCHITECTURE & INSTALLATION Q1 – Q10
══════════════════════════════════════
Question 1 of 50
A database administrator is installing a new SQL Server 2019 instance on a Windows
Server 2022 machine with 128 GB of RAM. During the installation, the DBA must decide
how to allocate memory between the operating system and the database engine. The
server will host only this single instance and no other major applications.
A. Reserve 8 GB for the OS and set the SQL Server max server memory to 120 GB
B. Reserve 20 GB for the OS and set the SQL Server max server memory to 108 GB ✓
CORRECT
C. Leave max server memory at the default unlimited setting and let SQL Server manage
everything
D. Reserve 4 GB for the OS and set the SQL Server max server memory to 124 GB
,Correct Answer: B
Rationale: Leaving adequate memory for the OS prevents paging and ensures Windows
can handle I/O operations and other background tasks without starving. Option A risks
OS instability under load, while option C allows SQL Server to consume everything and
potentially crash the host. A good rule of thumb is to reserve at least 4 GB for the OS
plus 1 GB for every 8–16 GB of RAM over 16 GB.
Question 2 of 50
A Linux administrator is preparing to install PostgreSQL 15 on a RHEL 9 server. The
organization requires that the database data directory, WAL files, and temporary
tablespace files reside on separate mount points for optimal I/O separation. The
administrator needs to identify the default location where PostgreSQL expects its
configuration files after a standard RPM installation.
A. /var/lib/pgsql/15/data/pg_hba.conf and postgresql.conf are stored in
/etc/postgresql/15/main/
B. /var/lib/pgsql/15/data/ contains postgresql.conf, pg_hba.conf, and pg_ident.conf by
default ✓ CORRECT
C. /opt/postgresql/15/conf/ is the standard RPM location for all configuration files
D. /usr/share/pgsql/15/ stores the active configuration files used by the running
instance
Correct Answer: B
Rationale: A standard PostgreSQL RPM installation places the data directory and
configuration files together under /var/lib/pgsql/15/data/. Option A describes the
Debian/Ubuntu path structure, not RHEL, and option C does not reflect the actual RPM
layout. Keeping configs in the data directory simplifies backup consistency since a base
backup captures both data and configuration state.
Question 3 of 50
,A company is migrating from a single MySQL 8.0 instance to a new architecture using
InnoDB Cluster for high availability. The DBA is reviewing the instance configuration and
notices that the innodb_buffer_pool_size is currently set to 2 GB on a server with 64 GB
of RAM. The database is approximately 45 GB in size and experiences heavy read
activity.
A. Increase the buffer pool to 48 GB to cache the majority of the working set
B. Increase the buffer pool to 32 GB to balance caching with OS and other process
needs
C. Increase the buffer pool to 48 GB, but no more than 75% of total system memory ✓
CORRECT
D. Leave the buffer pool at 2 GB and add read replicas instead
Correct Answer: C
Rationale: The InnoDB buffer pool should be large enough to cache the frequently
accessed portion of the dataset, but MySQL documentation recommends capping it
around 75% of total RAM to leave headroom for the OS, thread stacks, and other
buffers. Option A could cause swapping or OOM conditions, while option B might
under-utilize available memory for this read-heavy workload. In practice, monitoring
buffer pool hit rates after the change confirms whether the working set is adequately
cached.
Question 4 of 50
An Oracle DBA is configuring a new 19c database on an Exadata system. The storage
administrator has created ASM disk groups using both high-redundancy and
normal-redundancy policies. The DBA needs to place the database's critical SYSTEM
and SYSAUX tablespaces in a disk group that provides three-way mirroring to protect
against double disk failures.
A. Use the normal-redundancy disk group because it mirrors each extent twice
, B. Use the high-redundancy disk group because it provides three-way mirroring ✓
CORRECT
C. Use the external-redundancy disk group and rely on the storage array RAID for
protection
D. Use the flex-redundancy disk group because it automatically selects the best
protection level
Correct Answer: B
Rationale: ASM high redundancy creates three copies of each extent, ensuring data
survives even if two disks fail simultaneously. Option A describes normal redundancy,
which only provides two-way mirroring and cannot tolerate a double failure. Exadata
deployments often use high redundancy for critical metadata and application data
where downtime is unacceptable.
Question 5 of 50
A database team is deploying MongoDB 6.0 as a replica set for a new application.
During the architecture review, the lead DBA emphasizes that the oplog size must be
carefully chosen because it directly impacts how long a secondary can be offline before
requiring a full resync. The production environment expects sustained write throughput
of approximately 2 GB per hour.
A. Set the oplog to 16 GB, which provides roughly 8 hours of write coverage
B. Set the oplog to 24 GB, which provides roughly 12 hours of write coverage ✓
CORRECT
C. Set the oplog to the default 5% of free disk space regardless of write volume
D. Set the oplog to 4 GB because larger oplogs slow down replication on secondaries
Correct Answer: B
Rationale: The oplog must be large enough to retain all operations during the maximum
expected secondary downtime or maintenance window. Option C ignores the actual
write rate and could result in an oplog too small for recovery scenarios. MongoDB
