MongoDB Associate DBA - Study Strategy¶

Study Approach¶

Phase 1: Server Fundamentals (1-2 weeks)¶

1. mongod Configuration
2. Master mongod configuration file format
3. Understand WiredTiger storage engine internals
4. Learn journaling and durability mechanisms

5. Study server commands and diagnostics

6. Hands-on Setup

7. Install MongoDB locally and configure mongod.conf
8. Deploy standalone instance with custom configuration
9. Practice server management commands
10. Explore log files and server status output

Phase 2: Replication and Sharding (2-3 weeks)¶

1. Replication
2. Deploy a 3-node replica set
3. Practice elections and failover scenarios
4. Configure read preferences and write concerns

5. Study oplog mechanics and sizing

6. Sharding

7. Deploy a sharded cluster (config servers, mongos, shards)
8. Practice shard key selection for different workloads
9. Study chunk management and the balancer
10. Configure zone-based sharding

Phase 3: Security, Backup, and Monitoring (2-3 weeks)¶

1. Security
2. Configure SCRAM authentication
3. Set up TLS/SSL encryption
4. Implement role-based access control

5. Practice user and role management

6. Backup and Monitoring

7. Practice mongodump and mongorestore
8. Set up database profiler
9. Monitor with mongostat and mongotop
10. Analyze server metrics and performance

Phase 4: Exam Preparation (1 week)¶

1. Practice Exams
2. Take practice exams and review answers

3. Focus on Server Admin (25%) and Replication/Sharding (40% combined)

4. Final Review

5. Review configuration defaults
6. Review replica set member types and roles
7. Review shard key selection criteria

Study Resources¶

Official Resources¶

• 📖 MongoDB University - DBA Path - Free DBA courses
• 📖 MongoDB Administration - Admin reference
• 📖 Production Notes - Production guide
• 📖 MongoDB Manual - Complete reference

Practice¶

• 📖 MongoDB Atlas - Free tier for practice
• 📖 MongoDB Enterprise - Enterprise features
• 📖 MongoDB Tools - CLI tools reference

Exam Tactics¶

Domain Priorities (by weight)¶

1. Server Administration (25%) - Configuration and storage engine
2. Replication (20%) - Replica sets and failover
3. Sharding (20%) - Shard keys and cluster management
4. Security (15%) - Auth, roles, encryption
5. Backup/Recovery (10%) - Backup methods and restore
6. Monitoring (10%) - Metrics and profiling tools

Key Areas to Master¶

• mongod.conf structure and key settings
• WiredTiger cache sizing and behavior
• Replica set election rules and priority
• Shard key selection criteria and trade-offs
• Authentication methods and built-in roles
• mongodump/mongorestore options

Common Pitfalls¶

1. WiredTiger cache is not total memory - It uses 50% of RAM minus 1 GB by default
2. Arbiter cannot hold data - Only votes in elections
3. Shard key cannot be changed after collection is sharded (can refine with reshardCollection)
4. Oplog is capped collection - Fixed size, old entries removed automatically
5. Read preference secondary - May return stale data
6. w: "majority" not w: "all" - Majority is most common for strong consistency
7. mongodump is not a snapshot - Use with --oplog for consistency
8. Hidden members can vote - They just cannot be discovered by drivers