Questions

Linux and Fundamentals

1. How would you find out which process is using port 8080 on a Linux server?
2. What is the difference between a hard link and a symbolic link?
3. A disk is full but du shows plenty of free space. What might be happening?
4. Explain what file permissions 755 and 644 mean.
5. How do you check memory and CPU usage on a running server?

Networking

1. What happens, step by step, when you type a URL into a browser and press Enter?
2. What is the difference between TCP and UDP, and when would you use each?
3. What does a load balancer do, and what is the difference between Layer 4 and Layer 7 load balancing?
4. How would you troubleshoot a service that is reachable from inside a VPC but not from the internet?

Version Control and CI/CD

1. What is the difference between git merge and git rebase?
2. Describe a CI/CD pipeline you have built or maintained. What stages did it have?
3. How do you keep secrets out of a pipeline and out of source control?
4. What is a blue/green deployment, and how does it differ from a canary deployment?
5. How would you roll back a bad production deployment?

Containers and Orchestration

1. What is the difference between a container image and a running container?
2. In Kubernetes, what is the difference between a Deployment, a StatefulSet, and a DaemonSet?
3. A pod is stuck in CrashLoopBackOff. What are your first three troubleshooting steps?
4. What are liveness and readiness probes, and why do both exist?

Infrastructure as Code and Cloud

1. What is Terraform state, and why does it matter where it is stored?
2. What is the difference between immutable and mutable infrastructure?
3. How do you manage configuration differences between dev, staging, and production?
4. What is an IAM role, and why is it preferred over long-lived access keys?

Monitoring, Logging, and Reliability

1. What is the difference between monitoring and observability?
2. Name the three pillars of observability and give one tool for each.
3. What is an SLO, and how does it relate to an error budget?
4. You are paged at 2 AM for a high-latency alert. Walk me through your first ten minutes.
5. How do you avoid alert fatigue?

Security and compliance

1. How do you handle patching for a fleet of servers without causing downtime?
2. What is the principle of least privilege, and how have you applied it?
3. How would you scan container images for vulnerabilities before deploying them?
4. What steps would you take if a credential were accidentally committed to a repository?

Behavioral and judgment

1. Tell me about an outage you were involved in. What caused it, and what changed afterward?
2. Describe a time you automated something that was previously manual. What was the result?
3. How do you decide whether to build a tool in-house or adopt an existing one?
4. What would you do if a developer asked you to bypass a pipeline check to ship a hotfix faster?