WGU D330 – DATA SYSTEMS ADMINISTRATION
(OA EXAM) 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 company is deploying a new SQL Server 2022 instance to support a high-transaction
OLTP application. The server has two RAID arrays: Array 1 uses SSDs for the OS and
Array 2 uses NVMe drives for data. During installation, the DBA needs to configure the
default data, log, and tempdb file locations.
A. Place all database files, transaction logs, and tempdb on Array 1 to simplify backups.
B. Set data files on Array 2, transaction logs on a separate dedicated LUN, and tempdb
on Array 2 with multiple files. ✓ CORRECT
C. Store data and log files together on Array 2 and keep tempdb on Array 1 with the OS.
D. Use a single default file location on Array 2 and let SQL Server auto-grow all files
equally.
,Correct Answer: B
Rationale: Separating random-access data files from sequential-write transaction logs
prevents I/O contention and improves OLTP performance. Placing everything on the OS
drive creates a bottleneck and risks filling the system volume. Tempdb benefits from
fast dedicated storage but does not need to be isolated from user data files if the array
has sufficient throughput.
Question 2 of 50
An organization is migrating a 5TB Oracle 19c data warehouse from on-premises to
Exadata Cloud. The current environment uses RAID 5 for cost efficiency, but reporting
queries experience slow I/O during peak hours. The architect must recommend a
storage configuration for the new platform.
A. Continue using RAID 5 on Exadata to maintain consistency with the current backup
strategy.
B. Migrate to RAID 0 for maximum read performance without redundancy overhead.
C. Use RAID 6 with large stripe sizes to preserve disk space while adding fault tolerance.
D. Configure Exadata with ASM normal redundancy and smart flash cache for mixed
workloads. ✓ CORRECT
Correct Answer: D
Rationale: Exadata's architecture with ASM normal redundancy and flash cache is
designed specifically for Oracle workloads, balancing performance and fault tolerance.
RAID 0 provides no redundancy and is unacceptable for production data. RAID 5 and
RAID 6 introduce write penalties that degrade performance on Exadata's optimized
storage grid.
Question 3 of 50
,A PostgreSQL 15 database is being installed on a dedicated Linux server with 64GB of
RAM. The DBA is reviewing the postgresql.conf file to set memory parameters before
the database goes into production.
A. Set shared_buffers to approximately 16GB and leave effective_cache_size at around
48GB. ✓ CORRECT
B. Allocate shared_buffers to 56GB to maximize in-memory table storage.
C. Keep shared_buffers at the default 128MB and rely entirely on the filesystem cache.
D. Set shared_buffers to 32GB and work_mem to 2GB per connection for all 500
configured connections.
Correct Answer: A
Rationale: PostgreSQL performs best when shared_buffers is set to roughly 25% of
system RAM, allowing the OS filesystem cache to handle the remainder. Allocating too
much to shared_buffers can cause double buffering and memory pressure. The default
is far too low for production, and setting work_mem excessively high per connection
risks out-of-memory errors under concurrency.
Question 4 of 50
A MySQL 8.0 DBA is configuring a new primary server for a read-heavy web application.
The server has 32 CPU cores and 128GB RAM. During initial setup, the DBA needs to
size the InnoDB buffer pool and thread handling.
A. Set innodb_buffer_pool_size to 16GB and enable the thread_pool plugin with 32
threads.
B. Configure innodb_buffer_pool_instances to 1 to reduce memory fragmentation.
C. Set innodb_buffer_pool_size to 96GB and innodb_buffer_pool_instances to 16. ✓
CORRECT
D. Leave innodb_buffer_pool_size at default 128MB and increase max_connections to
5000.
Correct Answer: C
, Rationale: For a read-heavy workload, the InnoDB buffer pool should consume 50-75%
of available RAM with multiple instances to reduce contention on large memory
allocations. A single instance creates mutex contention under heavy load. The default
buffer pool size is completely inadequate, and excessive max_connections without
proper thread handling causes resource exhaustion.
Question 5 of 50
A SaaS company is designing a multi-tenant application backend using SQL Server.
Each tenant stores sensitive financial data, and compliance requires that no tenant can
access another tenant's data, even accidentally through application bugs.
A. Use a single database with a shared schema and enforce separation through
application-layer code only.
B. Deploy a database-per-tenant model with separate connection strings and credential
isolation. ✓ CORRECT
C. Use a single database with schema-per-tenant but grant all tenants access to the dbo
schema.
D. Host all tenants in one database filegroup and rely on row-level security without
tenant-specific schemas.
Correct Answer: B
Rationale: Database-per-tenant provides the strongest isolation boundary because each
tenant operates in a completely separate database with independent security contexts.
Schema-per-tenant with shared dbo access violates the compliance requirement by
exposing a common namespace. Relying solely on application code or row-level
security without proper schema architecture increases the risk of bypass vulnerabilities.
Question 6 of 50
After installing Oracle 19c on a new Windows server, the DBA notices the listener is
configured with default settings and no administrative password. The security team has
flagged this as a vulnerability in the initial scan.
(OA EXAM) 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 company is deploying a new SQL Server 2022 instance to support a high-transaction
OLTP application. The server has two RAID arrays: Array 1 uses SSDs for the OS and
Array 2 uses NVMe drives for data. During installation, the DBA needs to configure the
default data, log, and tempdb file locations.
A. Place all database files, transaction logs, and tempdb on Array 1 to simplify backups.
B. Set data files on Array 2, transaction logs on a separate dedicated LUN, and tempdb
on Array 2 with multiple files. ✓ CORRECT
C. Store data and log files together on Array 2 and keep tempdb on Array 1 with the OS.
D. Use a single default file location on Array 2 and let SQL Server auto-grow all files
equally.
,Correct Answer: B
Rationale: Separating random-access data files from sequential-write transaction logs
prevents I/O contention and improves OLTP performance. Placing everything on the OS
drive creates a bottleneck and risks filling the system volume. Tempdb benefits from
fast dedicated storage but does not need to be isolated from user data files if the array
has sufficient throughput.
Question 2 of 50
An organization is migrating a 5TB Oracle 19c data warehouse from on-premises to
Exadata Cloud. The current environment uses RAID 5 for cost efficiency, but reporting
queries experience slow I/O during peak hours. The architect must recommend a
storage configuration for the new platform.
A. Continue using RAID 5 on Exadata to maintain consistency with the current backup
strategy.
B. Migrate to RAID 0 for maximum read performance without redundancy overhead.
C. Use RAID 6 with large stripe sizes to preserve disk space while adding fault tolerance.
D. Configure Exadata with ASM normal redundancy and smart flash cache for mixed
workloads. ✓ CORRECT
Correct Answer: D
Rationale: Exadata's architecture with ASM normal redundancy and flash cache is
designed specifically for Oracle workloads, balancing performance and fault tolerance.
RAID 0 provides no redundancy and is unacceptable for production data. RAID 5 and
RAID 6 introduce write penalties that degrade performance on Exadata's optimized
storage grid.
Question 3 of 50
,A PostgreSQL 15 database is being installed on a dedicated Linux server with 64GB of
RAM. The DBA is reviewing the postgresql.conf file to set memory parameters before
the database goes into production.
A. Set shared_buffers to approximately 16GB and leave effective_cache_size at around
48GB. ✓ CORRECT
B. Allocate shared_buffers to 56GB to maximize in-memory table storage.
C. Keep shared_buffers at the default 128MB and rely entirely on the filesystem cache.
D. Set shared_buffers to 32GB and work_mem to 2GB per connection for all 500
configured connections.
Correct Answer: A
Rationale: PostgreSQL performs best when shared_buffers is set to roughly 25% of
system RAM, allowing the OS filesystem cache to handle the remainder. Allocating too
much to shared_buffers can cause double buffering and memory pressure. The default
is far too low for production, and setting work_mem excessively high per connection
risks out-of-memory errors under concurrency.
Question 4 of 50
A MySQL 8.0 DBA is configuring a new primary server for a read-heavy web application.
The server has 32 CPU cores and 128GB RAM. During initial setup, the DBA needs to
size the InnoDB buffer pool and thread handling.
A. Set innodb_buffer_pool_size to 16GB and enable the thread_pool plugin with 32
threads.
B. Configure innodb_buffer_pool_instances to 1 to reduce memory fragmentation.
C. Set innodb_buffer_pool_size to 96GB and innodb_buffer_pool_instances to 16. ✓
CORRECT
D. Leave innodb_buffer_pool_size at default 128MB and increase max_connections to
5000.
Correct Answer: C
, Rationale: For a read-heavy workload, the InnoDB buffer pool should consume 50-75%
of available RAM with multiple instances to reduce contention on large memory
allocations. A single instance creates mutex contention under heavy load. The default
buffer pool size is completely inadequate, and excessive max_connections without
proper thread handling causes resource exhaustion.
Question 5 of 50
A SaaS company is designing a multi-tenant application backend using SQL Server.
Each tenant stores sensitive financial data, and compliance requires that no tenant can
access another tenant's data, even accidentally through application bugs.
A. Use a single database with a shared schema and enforce separation through
application-layer code only.
B. Deploy a database-per-tenant model with separate connection strings and credential
isolation. ✓ CORRECT
C. Use a single database with schema-per-tenant but grant all tenants access to the dbo
schema.
D. Host all tenants in one database filegroup and rely on row-level security without
tenant-specific schemas.
Correct Answer: B
Rationale: Database-per-tenant provides the strongest isolation boundary because each
tenant operates in a completely separate database with independent security contexts.
Schema-per-tenant with shared dbo access violates the compliance requirement by
exposing a common namespace. Relying solely on application code or row-level
security without proper schema architecture increases the risk of bypass vulnerabilities.
Question 6 of 50
After installing Oracle 19c on a new Windows server, the DBA notices the listener is
configured with default settings and no administrative password. The security team has
flagged this as a vulnerability in the initial scan.
