easyMultiple ChoiceObjective-mapped
CV0-004 Practice Question: A deployment of a new application version fails…
A deployment of a new application version fails with a '503 Service Unavailable' error after a rolling update. The previous version was working. What is the most likely cause?
⚠ Common exam trap
Test-takers frequently assume a 503 error always means server overload or scaling issues, but CompTIA Cloud+ tests the nuance that a failing new version during a rolling update is more likely a dependency or configuration problem, not a capacity issue.
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
✓
New version missing a required dependency
A 503 Service Unavailable error during a rolling update typically indicates that the new application version cannot start or serve traffic. The most likely cause is a missing required dependency (e.g., a library, module, or runtime component) that the previous version did not need, causing the new pods or containers to fail readiness probes and be removed from the load balancer pool.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Database connection pool exhausted
Why it's wrong here
Would affect both versions equally.
- ✗
DNS propagation delay
Why it's wrong here
DNS changes do not usually cause 503 errors.
- ✗
SSL certificate expired
Why it's wrong here
SSL errors are different (e.g., certificate warning).
- ✓
New version missing a required dependency
Why this is correct
Missing dependency can cause health check failure, resulting in 503.
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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.