Section checkpoint

Design Problems

10 questions drawn from the 5 chapters in this section. If most land on the first try, you are ready for the next section. If not, the explanation after each answer says which idea to revisit.

Checkpoint

10 questions · first-try answers earn the most XP

1. Product wants click counts per link. Which redirect status keeps every click passing through your servers?

2. A link goes viral and one Redis node is serving 200,000 reads per second for that single key. What is the most direct relief?

3. Redis is down for 30 seconds. What does failing open mean, and why do many teams choose it?

4. Signed-in users are limited by user ID. What should anonymous traffic be limited by, and what is the catch?

5. Feed entries in the cache store only post IDs, not the posts themselves. What is the main benefit?

6. A user follows a new account. With fan-out on write, what should happen to their feed?

7. A 'your driver has arrived' push is sent while the user's phone is offline. FCM keeps undelivered messages for up to 28 days by default. What should you set?

8. Marketing emails go to millions of people a day. What do large mailbox providers such as Gmail now require of bulk senders?

9. Redis GEO members do not expire individually. A courier's app crashes and stops sending updates. What keeps dispatch from offering them orders?

10. The restaurant search service is down. What should the customer app do?

Design Problems

Checkpoint

What this checkpoint covers

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