>DevOps Interview KB

Comparison Interview Questions — All Categories

127 questions across 34 categories

Head-to-head trade-off questions — the kind that reveal whether a candidate has real judgment or just memorized facts.

How would you actually decide between Terraform, Pulumi, and a cloud-native tool like CloudFormation for a new project, beyond just 'what the team already knows'?

IntermediateTerraform7 min

When would you use Jenkins' built-in credentials store versus an external secrets manager like Vault for pipeline secrets, and what does each actually protect against?

IntermediateJenkins6 min

Your Jenkins controller has a fixed pool of static build agents. When would switching to ephemeral, on-demand agents (e.g. via Kubernetes) actually be worth the added complexity?

IntermediateJenkinsKubernetes6 min

How would Kaniko or rootless BuildKit avoid the Docker socket mounting problem entirely, and what do you give up by switching to them?

AdvancedJenkinsDocker7 min

If a Jenkins agent ran on Kubernetes instead of a static VM, how would troubleshooting the same Docker permission problem differ?

IntermediateJenkinsKubernetesDocker6 min

How do OPA Gatekeeper and Kyverno actually differ as policy engines for Kubernetes admission control, and which would you choose?

IntermediateKubernetesOpaKyverno6 min

For enforcing a new policy, when does it belong in a cluster admission webhook versus a CI-time check before deployment even happens?

IntermediateKubernetes6 min

What's the difference between HPA scaling on CPU utilization versus a custom metric like queue depth, and when is CPU actually the wrong signal?

IntermediateKubernetes6 min

You already enforce preventive admission policies (Kyverno/Gatekeeper) — why would you also need runtime security tooling like Falco?

AdvancedKubernetesFalco6 min

What's the difference between envFrom and individually listing env entries sourced from a ConfigMap/Secret, and when does it matter?

BeginnerKubernetes5 min

What's the difference between mounting a Secret as a volume versus injecting it as an environment variable, from a security perspective?

IntermediateKubernetes6 min

For distributing a complex application, when would you package it as a Helm chart versus building a dedicated operator for it?

AdvancedKubernetesHelm7 min

How does a Service-not-routing-traffic failure mode differ between a plain ClusterIP Service and one fronted by an Ingress controller?

IntermediateKubernetes7 min

What's the difference between Kubernetes Endpoints and EndpointSlices, and why did Kubernetes introduce EndpointSlices?

IntermediateKubernetes6 min

What's the difference between the older Ingress resource and the newer Gateway API, and when would you actually migrate?

IntermediateKubernetes6 min

How would you debug a Service routing failure differently if you were using a service mesh like Istio instead of plain kube-proxy-based Services?

AdvancedKubernetesIstio7 min

What's the difference between ClusterIP, NodePort, LoadBalancer, and ExternalName, and how do you choose?

BeginnerKubernetes5 min

What's the difference between a Role/RoleBinding and a ClusterRole/ClusterRoleBinding, and when would you bind a ClusterRole at namespace scope on purpose?

BeginnerKubernetes5 min

What's the difference in behavior between a container hitting its own memory limit versus the underlying node running out of memory overall?

IntermediateKubernetes6 min

How do requests.memory and limits.memory affect Pod scheduling and node-level eviction behavior differently from each other?

IntermediateKubernetes6 min

What's the practical difference between node affinity and a plain node selector, given affinity seems strictly more powerful?

BeginnerKubernetes5 min

What's the difference between requiredDuringSchedulingIgnoredDuringExecution and preferredDuringSchedulingIgnoredDuringExecution, and what incident does confusing them cause?

IntermediateKubernetes5 min

What's the difference between ReadWriteOnce, ReadWriteMany, and ReadWriteOncePod, and what production symptom does picking the wrong one cause?

BeginnerKubernetes5 min

How would your investigation differ if a Pod entered ImagePullBackOff instead of CrashLoopBackOff?

BeginnerKubernetes6 min