exclude a subdomain from a dns wildcard record
Normally when you define a wildcard record, it will only match if no other record matches. So if you have
example.com. A 8.9.10.11
*.example.com. A 4.5.6.7
host1.example.com. A 1.2.3.4
A wild card will only be matched if there is no subdomain defined. If you ask host1.example.com. it should return 1.2.3.4 and not 4.5.6.7
If this is the case, it might be that the changes haven't propagated yet. Use the dig to query your DNS server and some public server (google's is 8.8.8.8).