CV0-004 Troubleshooting Practice Question
Network Topology
The exhibit shows the health check status for targets in an application load balancer's target group. The target group has a health check on port 80. An administrator notices that one target is unhealthy on port 80 but healthy on port 443. 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
✓
The security group for the target is blocking port 80 from the load balancer.
The target is healthy on port 443 but unhealthy on port 80, indicating that port 80 is not reachable from the load balancer. The most likely cause is that the security group for the target is blocking inbound traffic on port 80 from the load balancer. Option A is incorrect because the target is healthy on 443, so the web server is listening on that port, but it could still be listening on 80; the issue is connectivity. Option C is incorrect because if the load balancer were in a different VPC, it wouldn't be able to communicate with any targets at all. Option D is incorrect because the health check path applies to both port 80 and 443 health checks if configured separately, but since only port 80 is failing and the path is the same, the path is not the issue.
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 web server on the target is not listening on port 443.
Why it's wrong here
The target is healthy on port 443, so the web server is listening.
- ✓
The security group for the target is blocking port 80 from the load balancer.
Why this is correct
A security group blocking port 80 would cause the health check on port 80 to fail, while port 443 remains healthy.
- ✗
The load balancer is in a different VPC.
Why it's wrong here
Same target group implies same VPC.
- ✗
The health check path is incorrect.
Why it's wrong here
An incorrect path would affect both ports if the same path is used, but the health check is on different ports.
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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.