Okay... Not sure if I'm being clear here. My point is, does the hostname that I pick for the machine matter?
Let's say the following is true:
domain.com --> I own this domain
domain.com --> resolve to 18.104.22.168
--> resolves to 22.214.171.124
ftp.domain.com --> resolves to 126.96.36.199
mail.domain.com --> resolves to 188.8.131.52
server1.domain.com --> NO A Record. Does NOT resolve.
Now, when installing ISPConfig 3 and setting up the server, can I set the hostname to server1.domain.com or does it have to resolve? (i.e. mail.domain.com)
Basically, I'm just trying to wrap my head around FQDN. Does FQDN only mean that it has to be in the form of subdomain.domain.com or does it mean that it must resolve.
There are just so many terms flying around and I've never been able to wrap my head around this part.
Also... I know that Falko mentioned that Postfix will have errors if it doesn't resolve. But, couldn't you put server1.domain.com that doesn't resolve and then configure Postfix to use mail.domain.com? I mean what happens when you use a mail server that is not on the same server as ISPConfig 3?