Sample questions
Aws Databases Rds DynamodbDifficulty 1
What is the primary purpose of enabling Multi-AZ on an RDS instance?
- aTo let multiple applications read from the database at the same time without connection limits
- bTo provide automatic failover to a synchronous standby in another Availability Zone✓
- cTo automatically scale read throughput by adding more read replicas across regions
- dTo reduce storage costs by compressing data across multiple Availability Zones
Explanation:Multi-AZ RDS maintains a synchronous standby copy in a different AZ purely for high availability — if the primary fails, AWS automatically fails over to the standby. It is not a read-scaling feature (that's what Read Replicas are for, option c), doesn't affect connection limits (a), and has nothing to do with storage compression (d).
Aws Databases Rds DynamodbDifficulty 1
Can an application send read queries directly to an RDS Multi-AZ standby instance?
- aYes, and doing so is the recommended way to scale read traffic
- bYes, but only if the application uses a read-only database user
- cNo — the standby is an inaccessible failover target✓
- dNo, because the standby is stored in an entirely different database engine format
Explanation:The Multi-AZ standby is a passive failover target — applications cannot connect to it directly for reads. For read scaling, you use Read Replicas instead, which are separately accessible endpoints. The standby stores data in the same engine format as the primary (d is wrong).
Aws Databases Rds DynamodbDifficulty 1
What kind of replication does an RDS Read Replica use to stay in sync with its source instance?
- aAsynchronous replication, meaning the replica can lag behind the source by some amount of time✓
- bSynchronous replication, meaning every write is confirmed on the replica before the source considers it committed
- cNo replication — the replica polls the source database on a fixed schedule and re-imports all data
- dTwo-way synchronous replication, so writes to the replica also propagate back to the source
Explanation:RDS Read Replicas use asynchronous replication — the source doesn't wait for the replica to apply changes before acknowledging a write, so some replication lag is normal and expected. This is different from the synchronous standby used in Multi-AZ. Read Replicas are also read-only by default; they don't write back to the source (d is wrong).
Aws Databases Rds DynamodbDifficulty 1
Which of the following best describes the main use case for RDS Read Replicas?
- aProviding automatic failover if the primary database instance becomes unavailable
- bEncrypting data at rest that was previously stored unencrypted
- cReducing the storage cost of the primary database instance
- dOffloading read-heavy workloads from the primary to increase read throughput✓
Explanation:Read Replicas exist to scale read capacity — you can point read-heavy workloads like reporting or analytics queries at a replica instead of the primary, freeing up the primary for writes. Automatic failover is a Multi-AZ feature, not a Read Replica feature (a); Read Replicas don't inherently change encryption (b) or reduce primary storage costs (c).
Aws Databases Rds DynamodbDifficulty 2
An engineer promotes an RDS Read Replica to be a standalone, writable database instance. What happens to its replication relationship with the original source?
- aNothing changes — the replica remains readable and continues silently replicating from the source in the background
- bThe source instance is automatically deleted once a replica is promoted
- cReplication ends permanently; the promoted instance becomes an independent database✓
- dThe replica and the source merge into a single Multi-AZ pair going forward
Explanation:Promoting a Read Replica permanently severs its replication link to the source — it becomes a fully independent, writable RDS instance from that point forward. This is a one-way, irreversible action often used for disaster recovery or splitting workloads. The source instance is unaffected and keeps running (b is wrong); nothing merges the two into a Multi-AZ pair (d is wrong).
Aws Databases Rds DynamodbDifficulty 1
What is a DynamoDB "partition key" primarily used for?
- aEncrypting individual items within a table
- bSelecting an item's storage partition by hashing the key value✓
- cDefining the sort order of all items returned by any query on the table
- dSetting the maximum size limit of the entire table
Explanation:DynamoDB hashes the partition key value to decide which internal physical partition stores the item — this is the core mechanism behind DynamoDB's horizontal scalability. Sort order within a partition is controlled by a separate sort key, not the partition key alone (c); encryption (a) and table size limits (d) are unrelated to the partition key's role.