System Design Foundations Checkpoint

Trace fresh cases, diagnose a failed invariant, then revisit the linked explanation and implementation.

Get every question correct to pass this checkpoint. You can review feedback, revise your answers, and submit again.

1. A service receives 1,200 requests/s and stores 2 KB per request, using decimal KB. How many MB are written in 10 seconds before replication? Answer with the integer only.

2. The requirement says "fast enough." Which clarification most helps choose an architecture?

Select one answer.

A measurable latency percentile, request mix, and load envelope The maximum number of boxes in a diagram A database brand before access patterns A preferred programming language alone

3. A daily average is 100 requests/s but the peak is 2,000/s. Which number should govern immediate serving capacity if no queueing is allowed?

Select one answer.

The peak workload with an explicit safety margin Zero because autoscaling is instantaneous The number of developers Only the daily average

4. An operation uses 20 ms of one fully occupied worker. Ignoring overhead, how many operations per second can that worker complete? Answer with the integer only.

5. A design promises both zero data loss and no synchronous replication delay. What must be examined?

Select one answer.

The number of colors in the diagram Only the frontend framework The failure model and acknowledgment point behind the durability claim Only the cache TTL

6. A product accepts stale recommendations but forbids stale inventory reservations. What follows?

Select one answer.

Remove all caching globally Force identical freshness for every endpoint Specify separate consistency requirements for those operations Treat every read as eventually correct enough

7. Two serial dependencies each report p99=80 ms. Is the request-path p99 therefore exactly 160 ms?

Select one answer.

No; it depends on the joint request durations and other path costs Yes; percentiles always add Yes; if they use the same programming language No; serial requests always take the maximum only

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