MongoDB Database Admin Sample Questions & Practice Test

MongoDB Associate Database Administrator is an operations route for candidates who manage replica sets, sharding, backups, restores, indexes, monitoring, security, and database troubleshooting.

Use this page to preview the kind of administration decisions a MongoDB DBA practice route should test. The questions below are original IT Mastery sample questions, not official MongoDB exam questions.

What this route should test

• administering availability, replication, sharding, backup, restore, security, and monitoring workflows
• diagnosing slow operations, replication lag, storage growth, index issues, and access failures
• understanding operational tradeoffs rather than memorizing command names only
• knowing when to escalate to application, data-modeling, network, or infrastructure owners

Sample Exam Questions

Question 1

Topic: replica sets

What is the main purpose of a replica set?

• A. To remove all indexes
• B. To store every collection in one document
• C. To provide redundancy and high availability through replicated data across members
• D. To disable elections

Best answer: C

Explanation: Replica sets maintain copies of data across members and can elect a new primary if the current primary becomes unavailable. They support availability, not automatic query optimization.

Question 2

Topic: replication lag

Secondaries are falling behind the primary. What should be reviewed?

• A. Network health, disk performance, workload volume, secondary resources, oplog behavior, and long-running operations
• B. Only the database name
• C. Whether dashboards are alphabetized
• D. The number of collections with short names

Best answer: A

Explanation: Replication lag can come from resource limits, network delays, heavy writes, slow operations, or oplog pressure. Administrators should look at evidence across the replica set.

Question 3

Topic: sharding

Why is shard-key choice important?

• A. It only changes dashboard colors
• B. It replaces backups
• C. It makes all fields unique
• D. It affects data distribution, query targeting, write distribution, and long-term scalability

Best answer: D

Explanation: A shard key drives how data is distributed and routed. Poor shard-key choice can create hot shards, scatter-gather queries, or scaling limits.

Question 4

Topic: backup and restore

Which statement best describes backup readiness?

• A. Backups remove the need for access control
• B. Backups should be configured and restore procedures should be tested against recovery requirements
• C. Backups make slow queries fast
• D. Backups are only useful if no one documents them

Best answer: B

Explanation: Backup readiness includes both having backups and proving that restore works within recovery objectives. Recovery is an operational process, not just a checkbox.

Question 5

Topic: index maintenance

Why should administrators monitor index usage?

• A. Every field must be indexed
• B. Indexes never consume storage
• C. Unused or excessive indexes can add storage and write overhead, while missing indexes can cause slow queries
• D. Indexes replace authentication

Best answer: C

Explanation: Indexes are a tradeoff. They improve selected reads but cost storage and write maintenance. DBAs should review query needs and index usage evidence.

Question 6

Topic: access control

Which practice supports secure database administration?

• A. Role-based access, least privilege, separate admin accounts, audit awareness, and credential rotation
• B. Shared root passwords in chat
• C. Disabled authentication
• D. Public backups

Best answer: A

Explanation: Administrative access should be controlled and auditable. Shared broad credentials increase risk and weaken accountability.

Question 7

Topic: slow operations

A slow-operation log points to a query scanning many documents. What should the DBA check?

• A. Only the user’s name
• B. Whether the server room has a window
• C. The collection’s creation date only
• D. Query filter, index availability, sort pattern, execution plan, and expected cardinality

Best answer: D

Explanation: Slow scans often relate to missing or mismatched indexes, broad filters, sort requirements, or data distribution. The DBA should review the query plan and workload context.

Question 8

Topic: elections

What can happen if the primary in a replica set becomes unavailable?

• A. All data is deleted
• B. Eligible members can elect a new primary if quorum and configuration allow
• C. Indexes are removed automatically
• D. The cluster becomes a relational database

Best answer: B

Explanation: Replica set elections support high availability. Election success depends on member health, votes, priority, and quorum.

Question 9

Topic: storage

Disk usage rises quickly after new indexes are added. What is the likely reason?

• A. Indexes always shrink data
• B. Disk usage cannot be affected by indexes
• C. Indexes consume storage and may grow significantly depending on fields and collection size
• D. Backups are disabled automatically

Best answer: C

Explanation: Indexes require storage. Adding multiple or broad indexes on large collections can materially increase disk usage.

Question 10

Topic: monitoring

Which metrics are useful for DBA health review?

• A. Connections, operation latency, replication lag, CPU, memory, disk I/O, storage, cache behavior, and slow operations
• B. Only the cluster name
• C. UI color preferences
• D. The number of comments in application code

Best answer: A

Explanation: Database health spans workload, resources, replication, and storage. Monitoring should provide enough evidence for trend review and incident response.

Question 11

Topic: restore scope

Why should restore scope be understood before starting a recovery?

• A. Restore scope is never relevant
• B. Restores cannot affect users
• C. Scope only changes the dashboard title
• D. The team must know whether it is restoring a collection, database, cluster, or point in time and what data may be affected

Best answer: D

Explanation: Recovery actions can overwrite or expose data depending on scope and timing. Administrators should understand impact before restoring.

Question 12

Topic: escalation

A query is slow after a new feature release, but database resources are normal. What should the DBA do?

• A. Blame the hardware immediately
• B. Gather query-plan and workload evidence, then coordinate with application and data-model owners
• C. Delete all indexes
• D. Disable backups

Best answer: B

Explanation: Slow queries after a release may be caused by query shape, data model, code paths, or index mismatch. The DBA should provide evidence and work with the owning team.

Quick readiness checklist

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