DOL Technical Expertise 3 — Questions and Answers
Question 1: A DevOps Leader notices that infrastructure drift is causing inconsistencies between environments. Which tool category directly addresses this problem?
- Log aggregation platforms
- Infrastructure as Code (IaC) tools (Correct answer)
- Application performance monitoring tools
- Container registries
Correct answer: Infrastructure as Code (IaC) tools
IaC tools like Terraform and Pulumi enforce desired state declaratively, preventing and detecting configuration drift across environments.
Question 2: What does the 'immutable infrastructure' principle mean in a DevOps context?
- Infrastructure that cannot be monitored or altered at runtime
- Servers are never modified in place; instead, new instances replace old ones (Correct answer)
- Database schemas cannot change after initial deployment
- CI/CD pipelines are locked after creation
Correct answer: Servers are never modified in place; instead, new instances replace old ones
Immutable infrastructure replaces rather than updates running servers, ensuring consistency and eliminating configuration drift.
Question 3: Which observability pillar provides the most direct insight into the root cause of a distributed system failure?
- Metrics
- Distributed traces (Correct answer)
- Logs
- Alerts
Correct answer: Distributed traces
Distributed tracing follows a request across multiple services, making it the most effective tool for pinpointing which service or component caused a failure.
Question 4: A team wants to validate that Terraform changes won't break production before applying them. Which Terraform command should be part of their CI pipeline?
- terraform apply -auto-approve
- terraform plan (Correct answer)
- terraform destroy
- terraform import
Correct answer: terraform plan
`terraform plan` generates an execution plan showing what changes will be made without applying them, enabling review and validation in CI.
Question 5: What is the main advantage of using a multi-stage Docker build?
- Faster container startup time at runtime
- Smaller final image size by excluding build-time dependencies (Correct answer)
- Automatic security scanning of base images
- Support for running multiple applications in one container
Correct answer: Smaller final image size by excluding build-time dependencies
Multi-stage builds separate build environments from runtime environments, so compilers and build tools are not included in the final production image.
Question 6: Which strategy should a DevOps Leader recommend to ensure database schema migrations don't cause downtime during zero-downtime deployments?
- Run migrations after all traffic is cut over to the new version
- Apply backward-compatible migrations before deploying new application code (Correct answer)
- Use a separate maintenance window for all schema changes
- Restore from backup if migration fails
Correct answer: Apply backward-compatible migrations before deploying new application code
Applying backward-compatible schema changes before code deployment ensures both old and new application versions can run simultaneously during the transition.
Question 7: In the context of SRE and DevOps, what does an Error Budget represent?
- The financial cost allocated for resolving incidents
- The allowable amount of downtime or errors based on the SLO target (Correct answer)
- The number of bugs permitted per sprint
- The maximum number of deployments per day
Correct answer: The allowable amount of downtime or errors based on the SLO target
An error budget is the acceptable level of unreliability derived from subtracting the SLO target from 100%, balancing feature velocity against reliability.
DOL Technical Expertise 3
A DevOps Leader notices that infrastructure drift is causing inconsistencies between environments.
Which tool category directly addresses this problem?