[Solved] Given this HTTP response header snippet:Cache-Control: max-age=0, must-revalidate ETag: "abc123"What happens when the browser sends a request with header If-None-Match: "abc123"? | Rest API

Rest API - Request and Response Format

Given this HTTP response header snippet:

Cache-Control: max-age=0, must-revalidate
ETag: "abc123"

What happens when the browser sends a request with header If-None-Match: "abc123"?

AServer returns 304 Not Modified if content unchanged

BServer returns full content ignoring ETag

CServer returns 500 Internal Server Error

DServer always returns 200 OK with new ETag

Step-by-Step Solution

Solution:

Step 1: Understand ETag and If-None-Match interaction
The ETag header is a unique identifier for the content version. The browser sends If-None-Match with the ETag value to check if content changed.
Step 2: Interpret Cache-Control and server response
With max-age=0 and must-revalidate, the browser asks server to validate content. If ETag matches, server responds with 304 Not Modified, saving bandwidth.
Final Answer:
Server returns 304 Not Modified if content unchanged -> Option A
Quick Check:
ETag + If-None-Match = 304 if unchanged [OK]

Quick Trick: ETag + If-None-Match = 304 Not Modified if same [OK]

Common Mistakes:

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