inspect-an-http-cache-header

name	inspect-an-http-cache-header
category	code
description	Inspect HTTP cache headers across request, response, browser, CDN, proxy, and origin context. Use when freshness, reuse, revalidation, privacy, or invalidation behavior is unclear.

inspect-an-http-cache-header

When to use

• Use for an exact authorized URL, method, identity, and network path.
• Do not cache private responses or expose credentials during capture.

Procedure

1. Record request method, URL, authorization, cookies, time, edge, and expected policy.
2. Capture Cache-Control, Age, Date, Expires, validators, Vary, status, and CDN headers.
3. Separate browser, shared cache, surrogate, and origin decisions.
4. Calculate freshness and revalidation against clocks and directives.
5. Repeat cold, warm, conditional, anonymous, and authorized requests.
6. Record privacy, variation, stale, purge, and path findings.

Failure plan

• Bypass shared caching when identity separation or directive meaning is unsafe.

Worked example

An authenticated page is reused because Vary omits the tenant header despite a seemingly short TTL.

Done

• A cache-header report records request context, directives, validators, age, variation, layers, and findings
• Cold, warm, conditional, clock, identity, tenant, privacy, and shared-cache checks verify behavior