A colleague says: "We moved from VMs to containers." The key difference between a container and a VM is:
A container (e.g. Docker) packages the application and its libraries but shares the host OS kernel, making it lightweight and fast to start. A VM includes a full guest OS, making it heavier. Containers are orchestrated at scale using tools like Kubernetes.
2 / 5
"We use a blue-green deployment strategy to avoid downtime." This means:
In blue-green deployment you maintain two identical environments (blue = current live, green = new version). You deploy to green, test it, then switch the load balancer to route traffic from blue to green. Rollback is instant — just flip the switch back. Compare with canary releases, which gradually shift traffic percentages.
3 / 5
Complete the sentence: "Rather than clicking through the console, we define all our servers and networking rules in YAML files — that's _____."
Infrastructure as Code (IaC) means provisioning and managing infrastructure through machine-readable definition files (not manual processes). Popular tools: Terraform (declarative, cloud-agnostic), Pulumi (imperative, your language), AWS CloudFormation. It enables version control, peer review, and reproducible environments.
4 / 5
In observability, what are the "three pillars"?
The three pillars of observability are: Metrics (numerical measurements over time, e.g. request rate, error rate, latency — often "RED" or "USE" method), Logs (timestamped records of discrete events), and Traces (end-to-end tracking of a single request across services). Tools: Prometheus + Grafana, Jaeger, OpenTelemetry, Datadog.
5 / 5
"Our service has an SLO of 99.9% availability." An SLO (Service Level Objective) is:
An SLO is an internal reliability target (e.g. 99.9% uptime, p99 latency < 200 ms). It's measured via an SLI (Service Level Indicator — the actual metric). An SLA (Service Level Agreement) is the external contract with customers that may reference SLOs. The gap between 100% and your SLO is your error budget — how much unreliability you're allowed before slowing down feature work.