Explain SRE architecture and troubleshooting scenarios

Explain the difference between a Pod and a Deployment in Kubernetes and describe the role of a Service. How would you debug a Pod that fails to start—list concrete steps and typical kubectl commands you would use. Define and contrast SLO, SLA, and SLI; if the actual error rate exceeds the SLO, what actions would you take and how would you prioritize them. Given a distributed system with elevated request latency, outline a structured troubleshooting approach across the network, load balancer, database, cache, and the service itself, including the specific metrics to check and experiments to run. Compare SQL and NoSQL data stores and describe scenarios where NoSQL is the better fit.