CDN Usage Test
The CDN Usage Test detects whether your website is being served through a Content Delivery Network (CDN) and identifies exactly which provider — Cloudflare, Fastly, AWS CloudFront, Akamai, Google Cloud CDN, Azure Front Door or one of the smaller specialised players. We inspect response headers, server signatures, IP-range registrations and cache-status indicators to give a definitive answer plus a real-time view of edge cache performance, the geographic location serving the request, HTTP/2-or-3 negotiation, and TLS termination at the edge. Without a CDN, every visitor on every continent waits for a round trip to your single origin server — typically adding 200-800 ms to Time to First Byte.
What This Tool Checks
- CDN provider detection from response headers (CF-Ray, X-Served-By, X-Cache, X-Amz-Cf-Id, etc.)
- Edge cache hit / miss / revalidate status
- Geographic edge location (POP) responding to your request
- HTTP/2 and HTTP/3 (QUIC) protocol support at the edge
- TLS version and certificate authority
- Brotli / gzip negotiated at the edge
- Origin shielding indicators (multi-tier CDN architecture)
- Approximate Time to First Byte vs. an origin-only baseline
Why It Matters for SEO
A CDN is the single largest performance and SEO improvement most sites can ship in one deploy. Without a CDN, every visitor waits for a round trip to your origin — 200 ms from across town, 400 ms from across the country, 800+ ms from another continent. With a CDN, static assets and (with stale-while-revalidate) HTML are served from the edge POP closest to the user, typically in 10-30 ms. That improvement compounds into faster First Contentful Paint, faster Largest Contentful Paint, lower bounce rates and measurably higher Core Web Vitals scores — all of which feed Google's page-experience ranking signal directly. CDNs also absorb DDoS and bot traffic, terminate TLS at the edge, negotiate HTTP/3, and cut origin bandwidth costs by 70-95%.
How to Fix It
Pick a CDN and put it in front of your origin (Cloudflare, Fastly, Vercel, Bunny.net and AWS CloudFront all have generous free or low-cost tiers). Point your DNS at the CDN, terminate TLS at the edge, enable Brotli and HTTP/3, then audit your Cache-Control headers so static assets cache for 1 year + immutable and anonymous HTML uses stale-while-revalidate. Re-run this test until the cache-status header shows HIT on repeat requests and the edge POP matches your visitor's region.
How It Works
We send a real GET request from our test infrastructure, parse every standard and provider-specific response header, then cross-check against published CDN IP ranges and behavioural fingerprints (e.g. CF-Ray means Cloudflare, X-Served-By plus X-Timer means Fastly, X-Amz-Cf-Pop means CloudFront). When the CDN exposes its cache state we report HIT / MISS / DYNAMIC. Edge location, protocol and compression details come from the live TCP / TLS / HTTP exchange, so the report reflects the exact path your real users see.
Common Mistakes to Avoid
- Running a global e-commerce or SaaS site directly off a single origin server with no CDN
- CDN is enabled but Cache-Control headers force MISS on every request (defeats the CDN entirely)
- Using a CDN for static assets but routing HTML straight to origin even though pages are anonymous
- Forgetting to enable Brotli / HTTP/3 at the CDN — both are usually one toggle
- Origin still serving the same large hero images uncompressed because the CDN does not transform on the fly
Quick Checklist
- CDN detected (Cloudflare, Fastly, CloudFront, Akamai or equivalent)
- Edge cache returns HIT on repeat requests
- HTTP/2 or HTTP/3 negotiated at the edge
- Brotli enabled for HTML, CSS and JS
- Static assets cached 1 year with immutable
- Anonymous HTML uses stale-while-revalidate