Real life usage of the X-Forwarded-Host header?

Question

I\'ve found some interesting reading on the X-Forwarded-* headers, including the Reverse Proxy Request Headers section in the Apache documentation, as well as the

Answer 1

X-Forwarded-Host just saved my life. CDNs (or reverse proxy if you'd like to go down to "trees") determine which origin to use by Host header a user comes to them with. Thus, a CDN can't use the same Host header to contact the origin - otherwise, the CDN would go to itself in a loop rather than going to the origin. Thus, the CDN uses either IP address or some dummy FQDN as the Host header fetching content from the origin. Now, the origin may wish to know what was the Host header (aka website name) the content is asked for. In my case, one origin served 2 websites.