X-Forwarded-Host vs. x-Forwarded-Server

What is the difference between the following titles?

• X-Forwarded-Host
• X-Forwarded-server

In a setup with Apache being the proxy and Tomcat being the origin server, I see both of these in the HTTP requests that reach Tomcat. The values ​​were (this is from my own code logging names and header pairs with actual caps that I ran into)

x-forwarded-host some-server
x-forwarded-server some-server.dept.some-uni.edu

      

        
        
        
      

    

Are these values ​​typical? Which of the two should I use to reliably recover the URL given by the browser? In my case, the browser sent a GET with a value some-server.dept.some-uni.edu

in the request url, which makes me think it is x-forwarded-server

more appropriate to recover the url. I believe this is somewhat at odds with the MDN documentation , which only mentions X-Forwarded-Host

and states that this is a "standard de facto header to identify the original host requested by the client" (and no documentation on x-forwarded-server

)

This Apache OTOH page describes both headers as follows:

• X-Forwarded-Host The original host requested by the client in the Host HTTP header.
• X-Forwarded-Server Hostname of the proxy server.

(I appreciate that in order to recover the url I also need X-Forwarded-Proto

and X-Forwarded-Port

)