CV0-004 Troubleshooting Practice Question
A company recently migrated an application to the cloud. The application uses a load balancer in front of multiple EC2 instances. After the migration, users report that they occasionally receive 'Connection refused' errors. The administrator checks the load balancer health check logs and finds that some instances are marked unhealthy intermittently. The application's health check endpoint returns HTTP 200 when tested manually from the admin's workstation. What 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
✓
Security group rules blocking the load balancer health checks
The load balancer health checks are failing intermittently because the security group rules are blocking the health check traffic from the load balancer. When the health checks are blocked, the instances appear unhealthy. Manual testing from the admin's workstation works because the workstation is not subject to those security group rules. Option A (short interval) would cause more frequent health checks, not intermittent failures. Option C (memory exhaustion) would cause persistent failures. Option D (incorrect IP binding) would also cause persistent failures. Therefore, the most likely cause is B.
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 health check interval is too short
Why it's wrong here
A short interval would cause more frequent health checks, not intermittent failures.
- ✓
Security group rules blocking the load balancer health checks
Why this is correct
If the security group blocks health check traffic, the load balancer may intermittently mark instances unhealthy.
- ✗
The instances are running out of memory
Why it's wrong here
Memory exhaustion would affect the entire application, not just health checks.
- ✗
The application is not binding to the correct IP address
Why it's wrong here
Incorrect binding would cause persistent health check failures.
Go deeper
Related to this question
About these practice questions
Courseiva writes every CV0-004 question from scratch — 977 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.