Daily DevOps Interview Questions Day #54

Daily Interview Questions for SRE and DevOps engineers

Question for the day:

We’re going to go through a production troubleshooting scenario today and the goal of this exercise will be to see how you get to the root of a problem. Let me know if this type of Question/Answer/response flow is something you’d be interested in the future?

Scenario

You're on-call and get paged: the service “user-profiles” is seeing high latency.
It backs the homepage and mobile app. p95/p99 SLOs are breaching, and support team is reporting slow loads and timeouts.

The backend is simple, here are the parameters

• Service runs in Kubernetes on AWS, and depends on Redis (cache) and Postgres (DB).

• The Kubernetes deployment has autoscaling enabled.

• No recent deploys.

• CPU and memory look normal at first glance.

What would be the first question you ask? As we go along, each question will be responded to with logs/diagrams etc.

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Answers

There are many flows to it but I think the first question most people would ask would be:

Q: Can I get an architecture breakdown or diagram of how everything works?

A: Sure you can

Essentially the flow is:

• User makes a request to load profile (e.g., homepage, app).

• Service checks Redis for cached user profile:

  • Cache hit → return result immediately.

  • Cache miss → query Postgres.

• Postgres returns user data.

• Service writes result to Redis for future cache hits.

• Return response to user.

Now that one understands the architecture, what is the next question?