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CV0-004 Practice Question: A load balancer log entry shows the above for a…
Exhibit
Refer to the exhibit. User-Agent: Mozilla/5.0 Status: 504 Gateway Timeout Upstream: 10.0.1.25:8080 Response Time: 30.001s
A load balancer log entry shows the above for a request. What is the MOST likely cause of the 504 error?
⚠ Common exam trap
CompTIA often tests the distinction between 502 (bad gateway, often DNS or upstream connection failure) and 504 (gateway timeout, upstream response delay), and candidates mistakenly attribute 504 errors to health check failures or DNS issues.
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 backend server took too long to respond to the request.
A 504 Gateway Timeout error from a load balancer indicates that the load balancer sent the request to a backend server but did not receive a timely response. The load balancer has a configured timeout value (often 30-120 seconds), and if the backend server fails to respond within that window, the load balancer terminates the connection and returns a 504. This is the most common cause of 504 errors in load-balanced environments.
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 DNS resolution for the domain name has failed.
Why it's wrong here
DNS failure would prevent connection, not cause a timeout after connection.
- ✓
The backend server took too long to respond to the request.
Why this is correct
The 30s response time exceeds typical timeouts, causing the gateway to timeout.
- ✗
The requested resource does not exist on the backend server.
Why it's wrong here
A missing resource would return a 404, not a 504.
- ✗
The load balancer's health check is misconfigured.
Why it's wrong here
Health check misconfiguration would affect routing but not cause a 504 for an individual request.
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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.