in the absence of a "master" param in /etc/salt/minion, the minion will try to tune into the DNS name "salt" in the local domain. So if you have internal DNS on domain
"saltstack", for instance, then creating a CNAME for "salt.saltstack" and pointing it at your master will allow minions to tune into your master without an /etc/salt/minion file present.
Of course, another option would be to deploy an /etc/salt/minion with a "master" param pointing at the master IP/hostname:
We generally recommend setting up a CNAME like in the first option though, because it allows you the flexibility to either
- not initially deploy an /etc/salt/minion config file,
- have the deployed /etc/salt/minion have a "master" param which points to a DNS name that can be easily re-assigned without affecting your initial deploy image.