What do Cache-Control and ETag do for HTTP caching?
PICTURE THIS: A REST CALL
Simple meaning
Cache-Control tells browsers and CDNs how long a response may be reused.
WHY — Caching instead of guessing?
Why interviewers care about Caching:
who only read docs from people who shipped.
and tied to Full Stack work.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Cache-Control tells browsers and
CDNs how long a response may be reused.
- 2Why it exists
ETag is a fingerprint
- 3the client sends If-None-Match
and can get 304 Not Modified.
- 4Static hashed React assets
can be cached for a long time
- 5Common mistake
API JSON usually cannot.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Cache-Control tells browsers and CDNs how long a response may be reused. ETag is a fingerprint