Thanks for the explanation @bamajr 
When i setup a droplet at digital ocean there is no FQDN involved i guess , just a hostname.
I never set up a FQDN, i can use DO DNS to point to a droplet or like in my case i use cloudflare as DNS. The hostname is allways the name of the droplet.
Its a bit confusing when i use mutiple domains on one droplet, no ?
Thanks