SOA-C02 Cost and Performance Optimization Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Upgrade to a larger instance size.

  Why it's wrong here

  Changing the DB instance class to a larger size provides more vCPUs and memory, which helps if the bottleneck is CPU or memory pressure. However, it is a capacity-upgrade action, not a configuration change, and it requires a reboot (or Multi-AZ failover) that may cause downtime. For the stated performance question, increasing instance size does not tune I/O behavior or offload read traffic, so it is not one of the two recommended configurations.

• ✓

  Enable provisioned IOPS on the DB instance.

  Why this is correct

  Enabling provisioned IOPS on the DB instance creates an io1/io2 storage volume with a fixed, predictable IOPS level, decoupling performance from burst balances. This gives consistent low-latency I/O for transactional workloads and avoids the variability of general-purpose SSD when sustained throughput is required. It directly addresses storage I/O performance, making it a correct configuration choice.

• ✓

  Create a read replica in the same AWS Region.

  Why this is correct

  Creating a read replica in the same Region allows SELECT-intensive traffic to be serviced by a separate read-only endpoint, reducing the primary instance's query load and freeing its resources for writes. Because the replica uses asynchronous replication, it may lag slightly, but same-Region placement minimizes network latency while enabling effective read scaling. This configuration is a correct answer because it improves overall performance for mixed workloads by distributing read operations.

• ✗

  Enable Multi-AZ deployment.

  Why it's wrong here

  Enabling Multi-AZ deployment provisions a synchronously replicated standby in another Availability Zone for failover, but this standby is not accessible for reads and does not share the primary's workload. In fact, each write transaction is synchronously replicated, which can increase write latency. Therefore, Multi-AZ is a high-availability feature, not a performance-tuning configuration.

• ✗

  Enable storage auto-scaling.

  Why it's wrong here

  Enabling storage auto-scaling automatically increases the allocated storage size when free space is low, helping to avoid the 'storage full' error that can stop the instance. However, it does not change the storage IOPS, throughput, or latency characteristics, so it cannot resolve an I/O bottleneck or improve response times. This makes it a capacity-management feature, not a performance configuration.

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