KCNA Kubernetes Fundamentals Practice Question
A team notices that a pod remains in 'CrashLoopBackOff' state after deployment. The application logs show 'Error: unable to bind to port 8080'. What is the most likely cause?
⚠ Common exam trap
The KCNA exam often tests the misconception that a 'CrashLoopBackOff' with a port bind error is caused by resource limits or probe misconfiguration, when in reality it points to a network-level port conflict on the host node.
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 port is already in use on the host node.
The error 'unable to bind to port 8080' indicates that the container process cannot open port 8080 for listening. The most likely cause is that another process on the host node is already using port 8080, preventing the container from binding to it. This is a classic port conflict scenario, where the host's network namespace has a port already allocated, and the container (even with its own network namespace) may be using host networking or the port is mapped from the host.
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 pod's resource limits are too low.
Why it's wrong here
Incorrect; low limits cause OOM or throttling, not bind errors.
- ✗
An environment variable has a typo in the Deployment spec.
Why it's wrong here
Incorrect; typos cause application errors, not port binding failures.
- ✗
The readiness probe is misconfigured.
Why it's wrong here
Incorrect; readiness probes affect service routing, not pod startup.
- ✓
The container's port is already in use on the host node.
Why this is correct
Correct; port conflict prevents binding, causing container to exit.
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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.