DBS-C01 Workload-Specific Database Design Practice Question
Exhibit
Refer to the exhibit.
Consider the following AWS CLI command output for an Amazon RDS instance:
{
"DBInstances": [
{
"DBInstanceIdentifier": "mydb",
"DBInstanceClass": "db.r5.large",
"Engine": "mysql",
"DBInstanceStatus": "available",
"MasterUsername": "admin",
"Endpoint": {
"Address": "mydb.abcdef123456.us-east-1.rds.amazonaws.com",
"Port": 3306
},
"MultiAZ": false,
"StorageType": "gp2",
"AllocatedStorage": 100,
"ReadReplicaSourceDBInstanceIdentifier": "mydb-primary"
}
]
}Based on the CLI output, what is true about this RDS instance?
⚠ Common exam trap
The trap here is that candidates see `ReplicaLag: 0` and assume it means no replication is happening or that it indicates a Multi-AZ setup, but in reality, a lag of 0 simply means the replica is fully caught up, and the presence of the field itself confirms it is a Read Replica, not a Multi-AZ standby.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The instance is a Read Replica of another RDS instance
The CLI output shows `ReplicaLag` with a value of `0`, which is a field that only appears when the RDS instance is configured as a Read Replica. A Read Replica maintains asynchronous replication from a source DB instance, and the lag metric indicates how far behind the replica is. Since the output includes this field, the instance must be a Read Replica.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The instance runs Amazon Aurora PostgreSQL
Why it's wrong here
Engine is mysql.
- ✗
The instance is a Multi-AZ deployment
Why it's wrong here
MultiAZ is false.
- ✓
The instance is a Read Replica of another RDS instance
Why this is correct
ReadReplicaSourceDBInstanceIdentifier is set.
- ✗
The instance uses Provisioned IOPS (io1) storage
Why it's wrong here
StorageType is gp2.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DBS-C01 exam.