Interview questions in DevOps & Cloud, page 27
What strategies reduce DAST scan time while maintaining security coverage?
It tests balancing security depth with CI velocity through DAST tuning. A strong answer covers incremental scans, parallel workers, scoped targets, and shift-left complements.
Capacity planning for a distributed cache
Track hit ratio, memory and eviction rate, throughput/latency, and connections; correlate with growth to forecast when to add capacity before the hit ratio or evictions…
Retries and circuit breaking in a mesh
Configure bounded retries with timeouts for transient errors, and a circuit breaker via outlier detection plus connection-pool limits to shed load from a failing dependency.
Design a workflow for managing security scanner vulnerabilities
This tests scaling security without developer noise fatigue. A strong answer covers centralized ingestion, severity SLAs with exploitability, auto-triage rules, and CI gates on critical findings only. A red flag is forcing manual review of all scanner output.
Federating reliability ownership to product teams
Build a self-service reliability platform (golden paths, paved roads), train teams and embed SLO/on-call practices, and govern with standards plus error budget…
Diagnosing latency with distributed tracing
Follow the trace ID across spans, compare per-span durations to find the slow hop, distinguish service time from network and queueing.
Design a golden path CI/CD pipeline for a Go API
Propose build, test, SAST, containerize, deploy stages with hooks or config overlays for flexibility.
Method-aware authorization with Istio policy
An ALLOW policy on user-service granting frontend's principal POST plus the users path, another granting all principals GET; deny is implicit once any ALLOW exists.
Guardrails for GitOps sync outages
Pre-merge schema validation, dry-run, policy gates and review; post-merge progressive sync, health checks with automated rollback, and pruning controls.
Istio Gateway vs Kubernetes Ingress
Ingress is a simple built-in L7 entry abstraction; an Istio Gateway configures only ports and hosts at the edge while VirtualServices do routing, unlocking mesh features.
What makes a process a container to the kernel
Namespaces isolate and cgroups limit, but also capabilities, seccomp filters, mount/pivot_root for the rootfs, and SELinux/AppArmor labels.
Container registries: public vs private
A registry stores and serves versioned image layers by digest; public registries are open and rate-limited, private ones add access control, scanning, signing and network isolation.
Impact of losing etcd quorum
Without quorum etcd goes read-only-ish and the API server cannot persist writes, so scheduling and changes stall, but kubelets keep running existing pods.
Scaling on queue length with the HPA
Expose queue length through an external metrics adapter behind the metrics API, point the HPA at that external metric with a target per pod; KEDA packages this.
Docker layers and build cache efficiency
Each instruction makes a content-addressed read-only layer stacked by a union FS; shared layers are pushed/pulled once, and ordering the Dockerfile so volatile steps come last maximizes cache reuse.
Image signing with Cosign vs trusting a digest
A digest proves content has not changed but not who produced it; Cosign cryptographically signs the digest so a verified key proves provenance, and policies enforce it at admission.
How mounted ConfigMap updates propagate to pods
Kubelet refreshes mounted files within roughly a sync period via an atomic symlink swap, but the app must reload on its own; env-var injection never updates.
Mesh control plane vs data plane availability
The control plane configures and distributes policy; the data plane is the sidecars carrying traffic with cached config, so a brief control-plane outage keeps existing traffic flowing but…
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