CDNs navigate your requests to the most optimal server. However, it is difficult to see the results. Follwing page show the CDN server information (reverse name, AS number, http variables (server location)) to see the navigation results on your enviroment by a javascript.
NOTE: CDN use Airport code (e.g. SFO, NRT) to mean the location
- Airport codes
Background
CDN’s server location
- Akamai
- GSLB: DNS based
- Server location: AS Number only (no geological information)
- Akamai AS: 20940, 16625
- Cloudfront
- GSLB: DNS based
- Server location: HTTP variable (X-Amz-Cf-Pop) and reverse name (e.g. server-13-249-166-18.nrt12.r.cloudfront.net)
- Cloudflare
- GSLB: Anycast
- Server location: HTTP variable (cf_ray)
- Fastly
- GSLB: Anycast + DNS based?
- Server location: HTTP variable (x-served-by)
- Google (not CDN but www.google.com)
- GSLB: DNS based
- Server location: reverse name (e.g. nrt13s54-in-f4.1e100.net)
- Google Media CDN
- GSLB: Anycast + tunneling?
- Server location: HTTP variable (x-cdn or X-Cache-Status)
Check script
- code
- internal
- It sends DNS requests to Google public DNS using DoH (DNS over HTTPS) with edns_client_subnet, and displays the returned IP address and reverse lookup hostname.
- DNS based CDN (Akamai, cloudfront)’s GSLB support public DNS and returns the IP address of the best server.
Request from Author
To display HTTP variables, I need to configure CORS on the target site (I use my own test sites for cloudflare, cloufront, and fastly for this purpose). However, I cannot configure Google Media CDN because Google has not given me permission to use it.
I am looking for someone who uses Google Media CDN and would like to help me.