CV0-004 Troubleshooting Practice Question
A cloud database cluster is experiencing replication lag. The primary node shows high write activity, and the replicas are on different availability zones. Which of the following is the most likely cause?
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
✓
Network latency between the primary and replica zones is high.
Network latency between availability zones is a common cause of replication lag in asynchronous replication setups, especially when the primary has high write activity. Option A is incorrect because synchronous replication would cause the primary to wait for acknowledgment from replicas, leading to write slowdown rather than lag on replicas. Option C is incorrect because insufficient storage on replicas would typically cause disk-full errors, not replication lag. Option D is incorrect because vCPU over-allocation on the primary primarily affects compute performance, not the replication process which is more sensitive to network and disk I/O.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Replication is configured as synchronous.
Why it's wrong here
Synchronous replication makes the primary wait for replica acknowledgement, which slows the primary rather than creating lag between a busy primary and its replicas. It is tempting because synchronous mode does affect write latency, and it would be the answer if the stem described slow commits on the primary.
- ✓
Network latency between the primary and replica zones is high.
Why this is correct
High inter-zone network latency directly delays log shipping from primary to replica, so each replica applies writes later than the primary commits them. Since the replicas sit in different availability zones, cross-zone round-trip time is the bottleneck driving the observed replication lag, not write volume alone.
- ✗
The replica nodes have insufficient storage.
Why it's wrong here
Insufficient replica storage would halt or fail writes on the replica entirely, producing replication errors rather than the lag caused by the primary's high write volume. It is tempting because storage exhaustion genuinely breaks replication, and it would be the answer if replicas reported disk-full events.
- ✗
The primary node's vCPU is over-allocated.
Why it's wrong here
Replication lag stems from the replicas applying writes more slowly than the primary generates them, so the bottleneck sits on the replica side, not the primary's vCPU allocation. It is tempting because over-allocation degrades a primary's own query performance, and that would be the answer if the primary itself were slow.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CV0-004 practice question is part of Courseiva's free CompTIA 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 CV0-004 exam.