No worries. I’m looking at Nginx as well.
From what I’m reading, it seems there cannot be wildcards in an A record, but there can on a CNAME, but only as the first part. .e.g.
*.example.com is ok, but not example.*
Similarly, in the VirtualHosts section, you can’t have any wildcards in the ServerName parameter, but you can have them anywhere in the ServerAlias, it seems.
<VirtualHost *:80>
DocumentRoot "/www/example.com"
ServerName example.com
ServerAlias *.example.*
</VirtualHost>
Seems to work with example.com, example.net, test.example.com, etc, as long as there’s an A or CNAME record for each…