I'm currently hosting a subdomain for a charity on Dreamhost. The charity is in control of the DNS records, and they're slow to update them.
So for example.com:
www.example.com -> A-record webserver mail.example.com -> A-record mail server
About a year ago, I asked them to create:
foo.example.com -> A-record to 220.127.116.11 (Dreamhost's particular web server)
Trouble is, Dreamhost could change that server's IP at any time. The charity is slow to change records, so this could create an extended outage.
Should this be an NS record? e.g.,
foo.example.com -> NS-record ns1.dreamhost.com, ns2.dreamhost.com, ns3.dreamhost.com ns[1-3].dreamhost.com -> foo.example.com is 18.104.22.168
Or is there another way to do this which I'm missing...? It might seem like an elementary question, but I'd like to get them to correct the record and add a new one, and I'd rather their site kept running :-)