System Design
Reliability & Fault Tolerance
6 practice questions. Free questions open a full answer guide; the rest unlock with Pro.
- One of your services depends on a downstream that occasionally gets slow or fails. Walk me through how you'd keep that downstream's degradation from cascading into an outage of your own service — which resilience patterns you'd apply, and how they interact.
- In a microservices system, one slow service starts causing failures that ripple out and take down seemingly unrelated services. What causes this cascade, and how do you design to prevent it?Go Pro
- A service you depend on for product recommendations starts timing out under load. How would you keep your own service responsive and protect it from being dragged down with the dependency?Go Pro
- Your service depends on several downstream services, and when one of them slows down your whole service starts timing out and falling over with it. How do you design your service so a single slow or failing dependency can't take you down with it?Go Pro
- You're operating a service in a single region and the business now wants it to survive losing an entire region. How would you set the recovery objectives and design the multi-region failover, knowing replication lag is real?Go Pro
- Leadership asks you to set the availability targets for a new platform and decide how much to invest in redundancy. How do you reason about SLAs, SLOs, and error budgets, and translate a target like 'four nines' into concrete architecture and operational decisions?Go Pro
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