DNS wildcard in Server 10.5

Apologies if this question has already been asked/answered. Did not find any topics with a wildcard search related to 10.5 server. Am trying to set a wildcard for my primary zone. For example to make http://domain.com point to www.domain.com I do not see a way to add a wildcard record ie: "*" in the DNS service through Server Admin. Any help doing this would be greatly appreciated. Thanks.