Troubleshooting Interview Questions — All Categories
141 questions across 32 categories
Real production incidents, spanning Kubernetes, AWS, Docker, Terraform, CI/CD, networking, and databases — diagnosing a specific symptom back to its actual cause, not textbook definitions.
Two mutating webhooks both touch a pod's containers field, and the final result isn't what either webhook intended alone — how do you diagnose and resolve this?
ExpertKubernetes8 min
Every pod creation cluster-wide suddenly starts failing with an admission webhook TLS error — what happened, and how do you recover quickly?
ExpertKubernetes8 min
A validating webhook is rejecting pod creations that look completely valid — how do you diagnose what it's actually objecting to?
AdvancedKubernetes7 min
kubectl apply --dry-run=server behaves unexpectedly for requests a webhook handles — what does a webhook's sideEffects field have to do with it?
AdvancedKubernetes6 min
The API server responds slowly to all requests — how do you determine whether etcd, the API server, or something else is the bottleneck?
ExpertKubernetes9 min
Why might an HPA be unable to scale a Deployment even with plenty of spare CPU capacity on existing nodes?
IntermediateKubernetes6 min
An HPA scales up rapidly during a spike, then flaps up and down repeatedly for the next hour — what's causing it, and how do you fix it?
AdvancedKubernetes7 min
Users report increasing latency under load, but the HPA isn't scaling the Deployment at all — how do you figure out why?
AdvancedKubernetes8 min
Why does setting only limits (no requests) on a container break HPA's CPU-based scaling calculation?
BeginnerKubernetes5 min
A workload is constantly OOMKilled despite having an HPA configured — why doesn't horizontal scaling fix this, and what should you actually do?
IntermediateKubernetes6 min
A Deployment's pods get evicted during scale-up because new nodes take too long to become ready — how would you close that gap?
ExpertKubernetes8 min
A security scan found the kubelet's API port reachable without authentication on some nodes — what can an attacker actually do with that, and how do you fix it?
ExpertKubernetes8 min
Enforcing readOnlyRootFilesystem across all pods breaks several applications that write temp files — how do you roll this out without breaking them?
IntermediateKubernetes6 min
An app reads an env var from a Secret, but after rotating the Secret's value, the running pod still uses the old one — why?
IntermediateKubernetes5 min
A custom resource is stuck in Terminating status indefinitely after being deleted — what's a finalizer, and how does it cause this?
AdvancedKubernetes7 min
Custom resources are being created and updated, but the operator managing them appears to have silently stopped reconciling — how do you diagnose it?
AdvancedKubernetes8 min
A custom resource is deleted, but the Deployments and Services an operator created for it are left orphaned in the cluster — why doesn't Kubernetes clean them up automatically?
IntermediateKubernetes6 min
How would you troubleshoot connectivity that works within a node but fails between pods on different nodes?
AdvancedKubernetes8 min
A pod resolves a Service's DNS name intermittently but not consistently — how do you investigate CoreDNS itself?
AdvancedKubernetes8 min
What does a pod's ndots DNS setting default to, and how can it cause unexpectedly slow external DNS lookups?
AdvancedKubernetes7 min
A NetworkPolicy is applied but pods that should be blocked can still communicate — why might it not be enforced?
AdvancedKubernetes7 min
You deploy a new version of a Kubernetes Deployment. The pods show Running and pass their readiness checks, but the Service in front of them stops routing traffic entirely. Where do you look?
IntermediateKubernetes10 min
A pod's ServiceAccount token was found in a public repo — what's your incident response, and how do you reduce blast radius for next time?
ExpertKubernetes8 min
A pod can read ConfigMaps but not Secrets in the same namespace, even though its Role looks like it should allow both — how do you find the gap?
IntermediateKubernetes6 min