Module 01 · Core concepts · Drill

Core concepts drill

Scenario prompts that check whether core concepts is usable under pressure. Answer out loud, then compare.

4 prompts20 minNew

0 of 4 graded

Prompt 1
A photo-sharing app has 20 million daily active users; each opens the app five times a day and views about 30 photos per session. Photos average 500 KB. Estimate peak read requests per second, daily photo bandwidth out, and say what those numbers imply for the architecture.
Say your answer out loud first. Thirty seconds is enough.
Prompt 2
You inherit a service: one load balancer, two API servers at 70 percent CPU each, one primary database with a nightly backup, DNS managed by a single provider. The business wants 99.9 percent availability. Walk the diagram and say what you change first and why.
Say your answer out loud first. Thirty seconds is enough.
Prompt 3
Average latency for the search endpoint is 60 ms, but the product team reports that the search page 'often hangs'. The page makes eight parallel backend calls. Explain what is happening and what you would measure and change.
Say your answer out loud first. Thirty seconds is enough.
Prompt 4
A fintech app stores account balances and also shows a live activity feed of recent transactions. The database team proposes one consistency setting for everything. How do you respond, using CAP and PACELC?
Say your answer out loud first. Thirty seconds is enough.