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.
An Ansible playbook reports "changed" on the same tasks every single run, even when nothing about the target host actually changed. Why, and how do you fix it?
IntermediateAnsible8 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
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 determine, after an S3 public-write exposure, exactly which objects were added, modified, or deleted if versioning wasn't enabled?
AdvancedAWSS37 min
A security scanner just flagged one of your production S3 buckets as publicly readable. Walk through how you'd respond in the first hour and prevent a repeat.
AdvancedAWSS3Security10 min
Your AKS cluster is under CPU pressure and pods are stuck Pending, but the cluster autoscaler isn't adding nodes. How would you troubleshoot it?
AdvancedAzureKubernetesAKS10 min
A new LoadBalancer-type Service in AKS has been stuck in 'Pending' with no external IP for twenty minutes. How do you actually diagnose this in Azure specifically?
IntermediateAzureKubernetesAKS6 min
A team converted their AKS cluster to a private cluster for security reasons. The next day, several engineers and a CI/CD pipeline can no longer run kubectl commands at all. How do you diagnose this?
AdvancedAzureKubernetesAKS7 min
During a live incident, how would you distinguish a genuinely slow autoscaler scale-up from one that's actually stuck and won't complete on its own?
IntermediateAzureKubernetesAKS7 min
An App Service using Managed Identity to call a storage account worked fine for months. After a Private Endpoint was added to that storage account, the App Service started failing to reach it. Why?
AdvancedAzureApp ServiceBlob Storage7 min
A Consumption-plan Azure Function triggered by new Blob Storage uploads is intermittently missing events during bursty upload periods — why, and how do you fix it?
AdvancedAzureAzure FunctionsBlob Storage7 min
An App Service deployment tested perfectly in staging, but broke immediately in production right after a slot swap. What's the most likely cause, and how do you investigate it?
IntermediateAzureApp Service6 min
Right after scaling an App Service plan from one instance to several, users started randomly getting logged out and losing cart contents. What changed, and how would you fix it properly?
IntermediateAzureApp Service6 min
A CI/CD pipeline that's authenticated successfully for months suddenly starts failing with an authentication error, right after the security team enabled a new Conditional Access policy. What's happening?
AdvancedAzure7 min
A Function App using Managed Identity to read a Key Vault secret works most of the time, but intermittently fails on startup with an authorization error. How do you actually diagnose this?
AdvancedAzureKey Vault7 min
A user was granted Contributor access to a single resource group, but they can see and modify resources across the entire subscription. How is that possible, and how do you audit for this?
IntermediateAzure6 min
A CI/CD pipeline that's deployed successfully for two years suddenly fails every run overnight, with no recent pipeline or code changes. How do you diagnose it, and prevent it happening silently again?
IntermediateAzure6 min
An Azure Pipelines YAML job runs fine on Microsoft-hosted agents but fails only on self-hosted agents with 'command not found' for a tool the job needs. Why, and how do you fix it?
IntermediateAzure Pipelines7 min
A lifecycle policy quietly moved a set of blobs to Archive tier months ago, and now someone urgently needs one back within the hour. What are your actual options?
AdvancedAzureBlob Storage7 min
A storage account's firewall was locked down to specific VNets for security, and now diagnostic logging and a few other first-party Azure integrations silently stopped working. What's actually happening?
AdvancedAzureBlob Storage6 min
A blob was accidentally overwritten with bad data, not deleted. Both soft delete and versioning are enabled on the account. Why doesn't 'undelete' bring back the good version, and what actually will?
IntermediateAzureBlob Storage6 min
A script that processes filenames from a directory listing works fine in testing, but breaks (or silently does the wrong thing) the moment a filename has a space in it. Why, and how do you fix it?
IntermediateBash7 min
A script has 'set -e' at the top, but a failing command inside a function doesn't stop the script the way you'd expect. Why not, and how do you fix it?
AdvancedBash7 min
A backup script runs perfectly when you execute it by hand, but fails silently every night when cron runs it. How would you debug it?
BeginnerBashLinux8 min