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.
What's the mechanism difference between how EC2's IMDS delivers credentials versus how Lambda delivers them to a function's environment?
AdvancedAWSLambda6 min
How would you make the case for the cost of a separate AWS account, if leadership pushes back on the added complexity?
IntermediateAWS6 min
How does the approach to workload identity and least privilege differ if a workload runs on ECS or Lambda instead of EC2?
IntermediateAWSECSLambda7 min
You inherit an EC2 workload that authenticates to AWS using an IAM user with AdministratorAccess. How would you migrate it to least-privilege access without causing an outage?
AdvancedAWSIAMEC212 min
How would you measure whether an IAM governance change (like an SCP blocking user creation) actually worked, six months later?
IntermediateAWS6 min
How would you prevent a new workload from ever being built directly on a static IAM user again, at an organizational level rather than case by case?
AdvancedAWS8 min
A detective scan finds dozens of pre-existing IAM users with active keys across many accounts. How would you prioritize remediation?
AdvancedAWS7 min
How would you design automated credential rotation to handle the overlap window safely, so the application never experiences an auth failure?
AdvancedAWS7 min
A third-party application only supports static AWS access keys and can't use an instance profile or role. How do you handle this without abandoning least privilege entirely?
AdvancedAWS8 min
Even after mitigating cold starts, a small amount of irreducible tail latency remains. How would you design the caller's retry behavior to handle that remaining tail?
AdvancedAWSLambda8 min
How would a circuit breaker's threshold and recovery behavior be tuned differently for a Lambda-backed service versus a traditional always-on service?
AdvancedAWSLambda7 min
How would you detect, from CloudWatch metrics alone, whether a Lambda function's tail latency problem is cold-start-driven versus something else?
IntermediateAWSLambdaCloudwatch7 min
How does AWS Lambda's execution environment reuse actually work, and why does that make cold starts disproportionately affect low-traffic or bursty functions?
IntermediateAWSLambda7 min
What idempotency key design would you use for a payment-related Lambda function, given the higher stakes of a duplicate execution?
AdvancedAWSLambda8 min
Why does Lambda initialization code placed outside the handler function only run once per environment, and how would you use that intentionally?
IntermediateAWSLambda6 min
What's the cost/latency trade-off of using Provisioned Concurrency versus just increasing a Lambda function's timeout to absorb cold starts?
IntermediateAWSLambda6 min
How does Provisioned Concurrency eliminate Lambda cold starts on demand, and what does that actually cost?
IntermediateAWSLambda6 min
What's the difference between Lambda Provisioned Concurrency and Lambda SnapStart, and when would each be the better fit?
IntermediateAWSLambda6 min
How would you size Provisioned Concurrency for a Lambda function with a predictable daily peak but otherwise low traffic?
IntermediateAWSLambda6 min
How would you design a synthetic load test to reproduce and measure Lambda's bursty cold-start pattern before it shows up in production?
AdvancedAWSLambda7 min
A Lambda function times out for about 2% of invocations, seemingly at random, but works fine when you test it manually. How would you track down the cause?
IntermediateAWSLambda10 min
How would you tune a hedge-request delay so it targets genuine cold-start tail latency without firing on every normal request?
AdvancedAWSLambda7 min
How would you audit all S3 buckets in an account for their current Block Public Access and policy configuration, at scale?
AdvancedAWSS37 min
How would you handle the allowlisting process for intentionally-public S3 buckets so it doesn't become its own source of friction or forgotten debt?
IntermediateAWSS36 min