In a simple and non-technical way, but that gives you room to advance:
- Point the DNS of all domains to the same server;
- Configure the web server (Nginx/apache/iis) to direct ALL to the same directory;
This will make your system accessible regardless of whether the user came from www.dominio1.com.br
or www.dominio48.com.lo
.
Hence it will be up to your application to identify this internally and do whatever you want.
If you look at the App Session controller, it might be tied to the domain and you need to handle.
If you implement more information to your question, I can implement more details here to facilitate.