CDN testing overview
A CDN sits between your users and your origin. When it works, cached assets arrive from a nearby edge node in milliseconds and your origin sees little traffic. When it fails (after a purge storm, a cache-key misconfiguration, or an unexpected cache miss at peak traffic), origin servers carry the full load of millions of concurrent requests. Latency climbs and errors spread. CDN testing shows you these failure modes before they happen in production.
What CDN testing covers
Section titled “What CDN testing covers”CDN testing is a set of techniques that together verify:
- Cache correctness: the CDN caches the right responses, for the right duration, with the right scope.
- Origin protection: the CDN reduces load on your origin and holds up when the cache is cold.
- Edge performance: users in each geography get responses from a nearby edge node, and latency shows it.
- Purge and invalidation behaviour: what the sudden origin traffic surge does when you purge a cached resource.
- Cache-key accuracy: requests that should share a cached copy share one, and requests that must not share one stay isolated.
MaxoPerf’s role in CDN testing
Section titled “MaxoPerf’s role in CDN testing”MaxoPerf tests CDN infrastructure the same way it tests any other HTTP endpoint. It generates realistic load from cloud load locations in several regions, asserts on response headers, and shows TTFB and latency percentiles in a results dashboard. For CDN testing, it gives you:
- Multi-region runners: generate load from several geographic locations at once and measure each region’s edge performance separately.
- Header assertions: assert on
Cache-Control,Age,X-Cache, and any CDN-specific response headers directly in your test scripts. - TTFB measurement: the run overview records Time to First Byte, the metric most sensitive to cache hit/miss state.
- Per-endpoint breakdown: label requests by URL pattern or asset type to compare latency across resource categories.
- Failure criteria: set p95 TTFB and error-rate thresholds that fail a run automatically if edge performance degrades.
Section map
Section titled “Section map”Find the page for your situation in this table.
| You want to… | Go to |
|---|---|
| Validate that responses are being cached and measure hit ratio | Cache hit/miss testing |
| Test what happens when cached content is purged or invalidated | Cache invalidation and purge testing |
| Verify origin protection and measure how much traffic the CDN absorbs | Origin shield and offload testing |
| Measure per-region edge latency from multiple locations simultaneously | Multi-region edge performance |
| Measure TTFB, large-asset delivery, compression, and HTTP/2 | TTFB and asset delivery |
| Understand cache-key composition, Vary headers, and cache poisoning risks | Cache key and Vary testing |
| Find ready-made scenarios for common CDN situations | Day-to-day CDN scenarios |
| Review do/don’t rules before running any CDN test | CDN testing do and don’t |
Reading order
Section titled “Reading order”If this is your first time testing CDN infrastructure, read in this order:
- Cache hit/miss testing: cache state basics and how to measure it.
- TTFB and asset delivery: which metrics matter for CDN performance.
- Multi-region edge performance: run your first geo-distributed CDN test in MaxoPerf.
- Origin shield and offload testing: verify origin protection under realistic load.
- Cache invalidation and purge testing: test the riskiest CDN operation.
- Cache key and Vary testing: validate cache-key logic and Vary header handling.
- Day-to-day CDN scenarios: apply it all to real-world situations.
- CDN testing do and don’t: final rules before you run in production.
Before you start
Section titled “Before you start”- You need a MaxoPerf workspace with access to at least two cloud load locations to exercise multi-region edge behaviour.
- Confirm you are authorized to generate load against the CDN endpoint. Most CDN providers permit load testing on customer-owned origins with prior notice. Check your provider’s terms. See CDN testing do and don’t for details.
- Run a smoke test against your CDN URL first to confirm basic reachability and check which headers the CDN returns.
- Read HTTP and REST load testing if you are new to writing HTTP test scripts in MaxoPerf.
Where to go next
Section titled “Where to go next”- Cache hit/miss testing: start with the basics.
- Multi-region edge performance: run your first geo-distributed CDN test.
- Cookbook: multi-region distributed load: the general multi-region recipe this section builds on.