CV0-004 Troubleshooting Practice Question
A cloud engineer is troubleshooting an issue where users cannot connect to a web application hosted on a cloud VM. The VM's security group allows HTTP (port 80) from 0.0.0.0/0, and the VM's OS firewall is disabled. The engineer can ping the VM's public IP from the internet. What is the most likely cause of the issue?
⚠ Common exam trap
Candidates often assume a ping success implies all services are reachable, but ICMP (ping) operates at the network layer (Layer 3) and does not test TCP port availability, so a running web server is required for HTTP connectivity.
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
✓
Web server service is not running on the VM
Since the OS firewall is disabled and the security group allows HTTP from 0.0.0.0/0, the only remaining layer that could block connectivity is the application itself. If the web server service (e.g., Apache, Nginx, IIS) is not running on the VM, it will not listen on TCP port 80, so HTTP requests will be refused even though network-level access is permitted. The ability to ping the VM confirms IP-level reachability, isolating the issue to the application layer.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
OS firewall is blocking port 80
Why it's wrong here
The OS firewall is disabled.
- ✗
Incorrect routing table on the VM
Why it's wrong here
Ping works, so routing is functional.
- ✗
Security group rule is applied to the wrong subnet
Why it's wrong here
The security group allows HTTP from anywhere, so it should work.
- ✓
Web server service is not running on the VM
Why this is correct
If the web server is not running, it won't respond on port 80, even though the network allows it.
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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.