I'm trying to wrap my head around the wonderful world on DNS.

I have created a zone file for example.com which contains:

@     A    1.2.3.4
*     A    1.2.3.4

However I am also setting up my local DNS, local.example.com which I have created a separate zone file for containing the following:

machine1     A    192.168.0.1
machine2     A    192.168.0.2

When I dig machine1.local.example.com it returns A record 192.168.0.1, great.

Sadly, badmachine.local.example.com returns 1.2.3.4, as does local.example.com.

I'm not sure of the best way to prevent this. If I add the following to the local.example.com empty A records are returned for the above 2 examples as is the behaviour I desire:

@     A
*     A

Is this allowed? Is this best practice, or am I doing things terribly wrong? I'm using PowerDNS with BIND backend.

Thanks for your thoughts!