Google Site Reliability Engineer Interview Questions

I would first stop the spread by reducing load, isolating failing components, or triggering fallback behavior. Then I would look for the root cause, such as a dependency outage, retry storm, or resource exhaustion. The reason I choose this approach is that cascading failures often get worse when systems keep retrying blindly. I would also think about circuit breakers, backpressure, and graceful degradation. If the interviewer wants more detail, I would explain how I would design the system to make cascading failures less likely in the first place.

I would first confirm whether the error rate is real and determine which endpoint, region, or customer segment is affected. Then I would compare the error spike to recent deploys, dependency changes, and traffic patterns. The reason I choose this approach is that error spikes often come from a narrow cause rather than a full outage. I would also inspect logs, traces, and saturation metrics to see whether the failure is at the app, network, or database layer. If needed, I would discuss rollback or mitigation while the investigation continues.

I would read the log file line by line, extract the error field with a pattern or parser, and keep a running count in a dictionary or map. The reason I choose this approach is that it is simple, memory-efficient, and scalable for large logs. I would also think about malformed lines, timestamps, and whether the script needs to group by time window as well. If the interviewer wants more detail, I would mention how I would make the script configurable for different log formats. The core idea is to show clean parsing and aggregation.

I would start by understanding traffic patterns, peak usage, growth trends, and resource consumption per request. Then I would estimate how much headroom the system needs and whether scaling is limited by CPU, memory, storage, or network. The reason I choose this approach is that good capacity planning prevents emergencies instead of reacting to them. I would also think about seasonality, failover capacity, and whether the service can autoscale safely. If needed, I would describe how I would review capacity regularly instead of treating it as a one-time task.

I would page when the issue affects users, violates an SLO, or needs immediate human action to reduce impact. If the issue is minor, self-healing, or informational, logging or creating a ticket may be enough. The reason I choose this distinction is that paging should be reserved for urgent problems so people stay responsive to real incidents. I would also think about severity levels and whether automation can handle part of the response before involving a person. If the interviewer wants more detail, I would discuss alert tuning and incident ownership.