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.
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
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
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
Under a traffic spike, your application starts throwing 'too many connections' errors from the database, even though the database itself isn't under heavy CPU or memory load. What's happening?
IntermediateDatabases7 min
A user updates their profile, immediately reloads the page, and sees their old data — but only sometimes. What's causing this, and how do you fix it?
AdvancedDatabases8 min
A widely-used open-source dependency your organization relies on is publicly disclosed as compromised — a malicious backdoor was found in a recent release. How do you respond?
ExpertDevSecOps9 min
Your build just pulled in a package from the public npm registry instead of your internal package with the same name, and it wasn't the version your team published. What's happening, and how do you respond?
AdvancedDevSecOps8 min
A widely-used third-party GitHub Action your pipelines depend on was compromised via a stolen maintainer token. What's your actual exposure?
AdvancedDevSecOpsGitHub Actions8 min
Two containers on the same Docker host can't talk to each other over the network, even though both are running. How would you debug the connection?
BeginnerDocker8 min
A Docker host's disk usage keeps growing even though containers are regularly removed — how do anonymous volumes cause this, and how do you clean them up?
IntermediateDocker6 min
A container fails to write to a bind-mounted directory with permission denied, even though the host directory has permissive permissions — why?
AdvancedDocker7 min
A container was recreated to deploy a new image version, and all its data disappeared — what went wrong with the volume configuration?
IntermediateDocker6 min
A function migrated from Gen 1 to Gen 2 started returning occasionally-wrong results under load — what changed, and how do you fix it?
ExpertGCPCloud Functions8 min
A Cloud Function's p99 latency is dominated by cold starts under bursty traffic — how would you mitigate this, and what's the actual cost trade-off?
IntermediateGCPCloud Functions7 min
A Pub/Sub-triggered Cloud Function occasionally processes the same message twice — is this a bug, and how do you actually fix it?
IntermediateGCPCloud FunctionsPub/Sub7 min
A Cloud Function has been silently failing for days with no alert firing — what's typically missing in the observability setup, and how do you fix it?
IntermediateGCPCloud Functions6 min
A Cloud Function times out mid-execution after partially completing a multi-step operation — what state does it leave behind, and how do you design around this?
AdvancedGCPCloud Functions7 min
After adding a Serverless VPC Access connector to a Cloud Function, cold starts got noticeably slower — why, and is this avoidable?
AdvancedGCPCloud Functions6 min
A Cloud Function works perfectly with the Functions Framework locally but fails immediately in production — how do you systematically narrow down why?
IntermediateGCPCloud Functions7 min
A browser-based app can list bucket contents but fails to upload directly to Cloud Storage with a CORS error — how do you fix the bucket's CORS configuration?
IntermediateGCPCloud Storage6 min
A bucket scan flags a bucket as publicly readable, but Public Access Prevention shows as enabled — how is that possible, and how do you investigate it?
AdvancedGCPCloud Storage7 min
Object versioning was enabled for safety, but a lifecycle rule deleting noncurrent versions caused the same data loss versioning was meant to prevent — how?
AdvancedGCPCloud Storage7 min
A teammate's work was lost after a force-push overwrote their commits on a shared branch. How would you recover it?
IntermediateGit7 min
A teammate resolved a merge conflict by keeping 'their' version of every conflicting hunk without actually reading the other side's changes. Why is that dangerous, and how should conflicts actually be resolved?
IntermediateGit6 min