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.
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
A ServiceAccount that worked fine before a deployment suddenly gets Forbidden errors on the Kubernetes API — how do you diagnose it?
IntermediateKubernetes7 min
A Deployment runs fine in the staging namespace but fails with RBAC errors in production — what's actually different?
IntermediateKubernetes6 min
How would you distinguish a genuine memory leak from a legitimately growing in-memory cache, using only Kubernetes-level metrics?
AdvancedKubernetesPrometheus8 min
Your container runs fine locally but repeatedly gets OOMKilled after you deploy it to Kubernetes. How would you investigate it?
IntermediateKubernetesContainers10 min
Two pods that should never co-locate keep landing on the same node — what's wrong with the anti-affinity rule?
AdvancedKubernetes7 min
A critical pod gets preempted by a seemingly lower-priority pod during a resource crunch — how do you investigate and prevent it?
AdvancedKubernetes7 min