Multiple URL for one Drupal 8 website configuration I want create one Drupal 8 website (one database) with changing contents depending of the URL the user used, I mean:  


If the user goes to the main URL http://foo.com, the main page of the website is loaded and contains some content generated for the http://foo.com URL
If the user goes to the main URL http://faa.com, the main page of the website is loaded and contains some content generated for the http://faa.com URL


I can manage that with Apache settings. But how can I configure Drupal? If a user uses the URL http://foo.com and then, he goes to the subpage /test, the URL must become http://foo.com/test.
But, if a user goes to the site with the URL http://faa.com and then, he goes to the subpage /test, I want the base URL still http://faa.com (http://faa.com/test).
I've handled this situation very easily by setting two different Apache VirtualHost with the same DocumentRoot.

The thing you have to be very careful is the page caching of Drupal. I recommend you to read the Cache Context document on Drupal 8 who is very helpful for your situation. By passing the "url" cache context on your different render arrays, you will prevent the content of a URL to be displayed on the other.

Drupal routing system doesn't take the domain name. So there'll be no problem and a user who go on a subpage from a domain name will stay on this domain name.