Senior DevOps Interview Questions
516 questions across 39 categories
Deeper trade-off and design questions — why a specific approach was chosen, what breaks at scale, and how to reason about a system you didn't build.
When would you actually prefer blue-green deployment over canary, even for a system where reliability is critical?
IntermediateCI/CD6 min
When does autoscaling actually save money compared to a well-chosen fixed capacity, and when can it end up costing more?
IntermediateAWSKubernetes6 min
Your architecture serves a large volume of data out to end users and other services, and data transfer/egress costs have become one of your largest line items. What architectural decisions actually reduce this?
AdvancedAWS8 min
Leadership wants to adopt a multi-cloud strategy specifically to reduce vendor lock-in and negotiate better pricing. What are the real cost trade-offs they might not be accounting for?
AdvancedAWSAzureGCP7 min
How would you decide what mix of Reserved Instances, Spot Instances, and On-Demand capacity to use across a workload with both steady baseline traffic and unpredictable spikes?
IntermediateAWS7 min
An audit finds most of your EC2 instances are running at under 15% average CPU utilization. How would you approach rightsizing them without risking a performance incident?
IntermediateAWS6 min
This month's cloud bill came in 3x higher than usual, with no corresponding increase in traffic or deliberate infrastructure change. How do you actually track down the cause?
IntermediateAWS8 min
What's the actual difference between RPO and RTO, and how does each change depending on whether you're designing for multi-AZ or multi-region failover?
IntermediateAWS6 min
In a real system with dozens of services, how would you decide which specific ones actually need multi-region treatment versus which can safely stay single-region?
AdvancedAWS8 min
What's the actual difference between designing for high availability across Availability Zones versus across Regions, and when do you actually need multi-region instead of just multi-AZ?
AdvancedAWS8 min
How would you evaluate whether to move an existing IaaS-hosted application to a PaaS, given the migration cost involved?
IntermediateCloud7 min
A customer asks how their data stays isolated from other customers on the same physical cloud infrastructure. What's actually happening under the hood to make multi-tenancy safe?
IntermediateCloud Fundamentals6 min
What operational risks does heavy reliance on SaaS introduce that IaaS or PaaS generally don't — vendor lock-in and data portability included?
IntermediateCloud6 min
Where does serverless (e.g. AWS Lambda) actually fit on the IaaS/PaaS/SaaS spectrum — does it fit cleanly into any of those three categories at all?
IntermediateAWS6 min
Leadership is nervous about 'vendor lock-in' and wants every architectural decision evaluated for portability across cloud providers. Is this concern well-founded, or often overstated?
IntermediateCloud Fundamentals6 min
How would you explain the security trade-off between containers and VMs to someone deciding whether to run untrusted third-party code?
IntermediateContainers6 min
What specific Linux namespace types exist, and what does each one actually isolate for a containerized process?
IntermediateLinuxContainers7 min
What actually changed between cgroups v1 and v2, and why did some container resource limit behavior change when a host migrated to a v2-only kernel/distro?
AdvancedContainersLinux7 min
Kubernetes dropped direct Docker support years ago in favor of containerd/CRI-O. What's the actual relationship between Docker, containerd, and CRI-O, and why did this change happen?
IntermediateContainersKubernetes7 min
What does it actually mean for a container image to be 'OCI-compliant,' and why does that matter beyond just being a compatibility buzzword?
IntermediateContainers6 min
A container keeps getting killed, and both the container's own memory limit and the host's overall available memory look potentially responsible. How do you determine which one actually caused it?
AdvancedContainersLinux7 min
How does a container image's layered filesystem actually work at the OS level — what makes writes inside a running container not modify the underlying image?
IntermediateContainersLinux6 min
Your containerized application's process count keeps growing over time, even though nothing appears to be leaking connections or memory. What's likely happening, and why is it specific to running in a container?
AdvancedContainersLinux7 min
How would you monitor a batched backfill in production to know it's progressing safely, not falling behind, and not causing replication lag?
AdvancedPostgresql7 min