Limit on CNAME records for subdomains

Try creating an A or CNAME record with * as the subdomain and your server's IP (A record) or domain (CNAME record) as the destination. If your host's control panel doesn't permit a wildcard, you'll have to contact them for help, or move your DNS to a third party.

The first thing you need to do is determine who actually serves authoritative answers for your domain name. A WHOIS lookup will tell you which DNS servers are the ones where you should be making changes.

Once that is determined, make the changes with the provider listed and get rid of everything else to avoid any future confusion.

Regarding wildcards vs. hostnames, do whatever you're comfortable with. In general, most DNS implementations will look for a hostname that's been specifically defined (i.e. an A record that directs to a specific IP address) and will fall back to a wildcard if none is found. Personally, I prefer to define each of my records individually. This way I know what I have and where it goes without any questions. Wildcards can be great if you have 300 hostnames that all need to go to the same place and they change all the time. If you only have a handful of hostnames and they don't change often, I'd opt for setting them up individually.

If you have a dozen hostnames that all need to go to the same IP, you can define one of them as an A record, and make the rest CNAME aliases of the first one. This way, you only need to update that IP address once.