SAP-C02 Continuous Improvement for Existing Solutions Practice Question
A company is using Amazon RDS for MySQL and notices that read replicas are falling behind the primary. The primary instance is experiencing high write traffic. What is the best solution to reduce replica lag?
⚠ Common exam trap
SAP-C02 often tests the misconception that Multi-AZ or Region placement affects read replica performance, when in fact replica lag is a function of the replica's own compute/IO capacity and the primary's write volume.
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
✓
Increase the instance class of the read replica.
Read replica lag under high write traffic on the primary is most often caused by the replica's inability to apply the relay log fast enough — i.e., insufficient CPU/IOPS on the replica itself. Increasing the replica instance class gives it more vCPU, memory, and baseline EBS throughput, allowing the SQL thread to apply binlog events faster and close the gap. This directly addresses the bottleneck (replica apply capacity) without touching the primary's write path.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Increase the instance class of the read replica.
Why this is correct
Replica lag under high write traffic often stems from the replica's insufficient compute to apply the primary's binary log changes. Increasing the read replica's instance class gives it more CPU and memory to replay writes faster, reducing lag.
- ✗
Enable Multi-AZ on the primary instance.
Why it's wrong here
Multi-AZ maintains a synchronous standby for failover, not for serving reads, so it neither absorbs replica read load nor accelerates binlog shipping to existing read replicas. It is tempting because Multi-AZ does add a second instance, but that standby is unavailable for reads and would be the right choice for high-availability failover, not replica lag.
- ✗
Disable binary logging on the primary.
Why it's wrong here
Disabling binary logging removes the very mechanism read replicas use to replay changes, so replication stops entirely rather than catching up. It is tempting because binary logging adds write overhead on the primary, and disabling it would be correct for a standalone instance needing maximum write throughput with no replicas.
- ✗
Move the read replica to the same AWS Region as the primary.
Why it's wrong here
Cross-Region placement adds network latency to replication, so co-locating replicas in the same Region as the primary is already the default and cannot reduce lag caused by write volume. It is tempting because Region distance does affect replication delay, and this would be the right fix for lag caused by cross-Region network latency.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This SAP-C02 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 SAP-C02 exam.