DSA Factory
Free Names and the web lessonsNames and the web · Stage 0 · Names · Step 2

DNS records and their time to live

Learn the record types you meet in practice, and the trade-off in choosing a TTL. About 12 minutes.

Quick check

You are about to move your website to a new server and change its A record. What should you do beforehand?

  1. ALower the record's TTL ahead of time, so caches expire it quickly after the change
  2. BRaise the TTL so that fewer resolvers ask
  3. CNothing: DNS updates are pushed to everyone instantly
Show the answer

Lower the record's TTL ahead of time, so caches expire it quickly after the change. Caches can't see the new address until the old TTL runs out.

Lock it in

4 questions on this idea

Short questions that apply the idea to new cases: trace it, work out a number, put steps in order. A wrong answer explains itself.

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