CDN

What CDN means

It improves delivery but can preserve stale, transformed, or client-specific variants.

Where CDN comes up on this site

• XML sitemap audit: check the file and every URL in itThe redirect in front of it is uncached at both the CDN and the origin's page cache, so every request for the conventional path pays a full origin round trip: 954, 1,562 and 1,138 milliseconds on three consecutive scans .
• HTTP status codes for crawlers: what a 200 can hideThe CDN's cache-status header and the object's age expose it, and the fix is a purge, not a rule change.
• Stale cached robots.txt or llms.txt? Two fetches tell yourobots.txt, llms.txt, sitemap.xml and an entity map are small files that rarely change, which is exactly what a CDN caches hardest.
• Text-to-HTML ratio: does it matter, and how to check itWhat to remove first Re-measure after each change, and re-measure through the CDN: a cached copy of the old page keeps serving the old ratio until it is purged.
• How to verify Googlebot, GPTBot and other crawlers by IPBehind a CDN If the site sits behind a CDN or reverse proxy, the IP in the origin's logs is the proxy's, not the crawler's.

Terms this definition uses

ARIA

Definitions that name CDN

Edge transformation · Origin server · Edge node · 502 response · Edge redirect · edge cache

Related terms in HTTP, edge and rendering

The delivery layer between an origin and a client: proxies, caches, redirects, status codes and the headers that decide what a crawler actually received.

Content-Language header · HTTP/3 · Alt-Svc · HTTPS DNS record · Link header · content negotiation · Markdown negotiation · Retry-After · Server-Timing · WWW-Authenticate · Allow header · Content-Digest · Origin server · Reverse proxy · Edge node · WAF · Bot score · TLS handshake · DNS resolution · DNS timeout · Connection timeout · Read timeout · Redirect chain · Redirect loop · 301 redirect · 302 redirect · 307 redirect · 308 redirect · 304 response · 404 response · 410 response · 429 response · 500 response · 502 response · 503 response · 504 response · HEAD request · GET request · Content type · MIME sniffing · Content encoding · Compression · Brotli · ETag · Last-Modified · If-None-Match · Cache hit · Cache miss · Cache key · Vary header · Stale response · Stale-while-revalidate · Edge redirect · Origin bypass · Response parity · Header parity · hreflang · canonical URL · HSTS · HSTS preload list · Content-Security-Policy · CSP nonce · edge cache · cache split · cache-buster · Cache-Control · Age header · render-blocking resource · payload text share · lazy loading · 404 and 410 status codes

Questions about CDN

What is CDN?

A distributed network that serves content near clients and absorbs traffic from the origin.

Which area of the glossary does CDN belong to?

HTTP, edge and rendering: The delivery layer between an origin and a client: proxies, caches, redirects, status codes and the headers that decide what a crawler actually received.

← Reverse proxy  ·  Edge node →

See it in the full glossary · 772 terms across 19 areas.