Overview
Fastly’s edge network is announced from AS54113. Like Cloudflare, Fastly uses anycast — the same IP responds from every PoP, with traffic routed to the closest one. Fastly publishes its complete edge IP list via a public REST endpoint (/public-ip-list), updated as PoPs are added or rotated.
Services on these IPs
Fastly hosts: CDN/proxy for high-profile customers, Compute@Edge (WebAssembly serverless), image optimization, Fastly NextGen WAF (Signal Sciences), and log streaming. A single Fastly IP can front thousands of sites via TLS SNI.
How to detect Fastly IPs
Fastly adds an "X-Served-By" and "X-Cache" header on HTTP responses identifying the PoP. AS54113 + the /public-ip-list endpoint are the authoritative ownership checks. Reverse DNS often returns no PTR or a customer-controlled one.
When this matters
Origin allowlisting — only allow Fastly IPs to reach the backend. Threat hunters identify which sites a suspicious request was destined for via SNI. Network admins differentiate Fastly traffic from other CDNs.