---
title: CDN monitors now watch caching, not just the provider name
description: A CDN monitor that only told you which provider was in front answered a question you already knew the answer to. It now measures whether the edge is actually…
canonical: https://watchfor.io/changelog/2026-09-10-cdn-monitor-measures-caching
---

[All updates](/changelog/page/3#2026-09-10-cdn-monitor-measures-caching) ⚡ Improved Sep 10, 2026 · v 7.2.5

# CDN monitors now watch caching, not just the provider name

A CDN monitor that only told you which provider was in front answered a question you already knew the answer to. It now measures whether the edge is actually caching your URL and how fast it responds, with charts for hit ratio, time to first byte and latency by region, and alert rules for the failure that really costs you — caching quietly stopping while everything still looks up. New metrics: `cdn.cache_hit_ratio`, `cdn.ttfb_ms` and `cdn.status_code`. Over the API the target may now include a path, because `/` and `/static/app.js` rarely cache the same way.

Hit ratio, time to first byte and every check's cache result, over the last 24 hours.

Alert presets for the failures an uptime check misses.

## The failure it is built for

Caching usually stops quietly. A deploy changes a Cache-Control header or a CDN rule gets removed. The site stays up and every response is still a 200, but every request now goes to your origin, so pages get slower and your servers carry the load. An uptime check never notices.

## What the monitor measures

- Each check makes two requests in a row, so it can tell "not cacheable" from "not cached yet". If you only want provider detection, switch this off under Settings → Measure cache behaviour .

- The Overview tab charts the cache hit ratio and time to first byte (median and 95th percentile), latency by region when the monitor runs from more than one, and a strip with one block per check: hit, miss, not cached by design, or failed.

- New alert presets: Cache Stopped Working (hit ratio below your threshold, 50% by default), Edge Response Slow (time to first byte above 1000 ms by default) and Error Status Returned (the edge answers with a 4xx or 5xx).

- For your own rules: cdn.cache_hit_ratio (0 to 1), cdn.ttfb_ms and cdn.status_code .

## An example

A release adds Cache-Control: private to /static/app.js . Nothing breaks, so nobody looks. On the CDN monitor for that URL, the hit ratio falls from close to 100% to zero within a few checks, Cache Stopped Working fires, and the chart shows exactly when it started.

## Good to know

Point the monitor at an asset you expect to be cached, not your homepage. A page the edge deliberately does not cache, such as a logged-in view, sits at a hit ratio of 0 all the time.

Setup and every preset: [CDN monitoring docs](/docs/monitors/performance#cdn).

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Canonical page: https://watchfor.io/changelog/2026-09-10-cdn-monitor-measures-caching · Site guide: https://watchfor.io/llms.txt