A GET arrives with both If-None-Match and If-Modified-Since, and the two conditions disagree. What does RFC 9110 require?
Evaluate If-Modified-Since first, since date validators are cheaper to compare
Evaluate If-None-Match and ignore If-Modified-Since✓Correct answer
Evaluate both; respond 304 only if both indicate the stored copy is current
Respond 412 (Precondition Failed), since the preconditions conflict
Explanation
The precedence order is normative: If-Modified-Since is evaluated only when If-None-Match is absent, because entity tags are presumed more accurate than date validators. A disagreement between the two is therefore not an error condition.