Q:

Traffic NGIX to several backends

I saw many questions and answers for same subject but I'm still not convinced about my use case.
In my topology I have:

One server with NGINX / FastCGI for Wordpress multisite (subdomains)
One server with NGINX / FastCGI for API's (written in PHP)
One server with NGIX proxying a NodeJS app for socket connections

This is all using same domain name. Each server with its own public IP
For Wordpress, it manages itself the subdomains redirections.
For API's I also have subdomains for each API server { listen 80; server_name sub.xx.com....
For NodeJS is just an Upstream 
Is that possible to concentrate all requests into one IP, thus one NGINX, and let this guy dispatch the requests for the right server ?
The back servers need to have NGINX too ?
The question states mainly on Wordpress multisite and non-php content being served by a third server, as for fast_cgi I can proxy_pass to my fast_cgi instance IP:Port on back server.

A:

Simple answer - Yes. You could configure multiple domains on one nginx frontend and forward all requests to one or more backends.

