KCNA Kubernetes Fundamentals Practice Question
A pod in a ReplicaSet is failing with 'CrashLoopBackOff'. 'kubectl logs pod' shows 'Error: listen tcp :8080: bind: address already in use'. What is the most likely cause?
⚠ Common exam trap
CNCF often tests the distinction between pod startup failures caused by resource constraints or probe misconfiguration versus application-level port conflicts that arise from improper signal handling during restarts.
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 container's process is not terminating quickly enough on SIGTERM, causing a port conflict on restart.
The error 'address already in use' on port 8080 indicates that when the container restarts, the previous process is still holding the port. This typically happens when the application does not handle SIGTERM properly and does not shut down within the terminationGracePeriodSeconds (default 30s), so the old process lingers while the new one tries to bind to the same port, causing a CrashLoopBackOff.
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 readiness probe is misconfigured.
Why it's wrong here
Readiness probe doesn't affect port binding.
- ✗
The container image is missing the application binary.
Why it's wrong here
Missing binary would give 'command not found'.
- ✓
The container's process is not terminating quickly enough on SIGTERM, causing a port conflict on restart.
Why this is correct
Old process still holds the port.
- ✗
The pod is using hostPort and two pods on the same node conflict.
Why it's wrong here
hostPort would cause conflict across pods, but single pod restart shows the same pod.
Go deeper
Related to this question
About these practice questions
Courseiva writes every KCNA question from scratch — 833 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 KCNA practice question is part of Courseiva's free CNCF 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 KCNA exam.