HTTP caching headers in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of HTTP caching headers?

HTTP caching headers tell browsers and servers how to store and reuse web resources to make loading faster and reduce network traffic.

intermediate

Explain the difference between Cache-Control: no-cache and Cache-Control: no-store.

no-cache means the browser must check with the server before using cached data. no-store means the browser should never save the response at all.

intermediate

What does the ETag header do in HTTP caching?

The ETag is a unique identifier for a resource version. Browsers send it back to the server to check if the resource changed, so they can avoid downloading it again if unchanged.

beginner

How does the Expires header work?

The Expires header tells the browser a specific date and time after which the cached resource is considered stale and must be fetched again.

intermediate

What is the role of Last-Modified header in caching?

The Last-Modified header shows when the resource was last changed. Browsers use it to ask the server if the resource has changed since that date to decide if they need to download it again.

Which HTTP header tells the browser to always check with the server before using cached content?

A ETag

B Cache-Control: no-cache

C Expires

D Cache-Control: no-store

Cache-Control: no-cache means the browser must revalidate with the server before using cached content.

What does the ETag header help with?

A Identifying resource versions for validation

B Setting cache expiration date

C Preventing caching entirely

D Specifying content type

ETag is a unique tag to identify resource versions and help browsers check if content changed.

If you want to prevent any caching of a response, which header should you use?

A Expires: 0

B Cache-Control: no-cache

C Cache-Control: no-store

D Last-Modified

Cache-Control: no-store tells browsers not to save the response at all.

Which header specifies a date/time after which cached content is stale?

A Last-Modified

B Cache-Control

C ETag

D Expires

Expires sets a specific expiration date/time for cached content.

How does the Last-Modified header help caching?

A It tells the browser when the resource was last changed

B It disables caching

C It sets the cache duration

D It identifies the resource version

Last-Modified shows when the resource last changed, helping browsers decide if they need to reload it.

Describe how HTTP caching headers improve website performance and reduce server load.

Think about how your browser can save time by not downloading the same files again.

Explain the difference between Cache-Control: no-cache and Cache-Control: no-store headers.

One lets you keep data but checks before use; the other never saves it.