Problem

How to exclude distribution groups and contact records from queries to Active Directory?

Resolution

The default "Alias Query" value located under Admin UI > Administration > Directory Services > LDAP source is:
(proxyAddresses=smtp\3A%s).

If you need to skip the distribution groups and AD contacts, you can use the following Alias Query:
(&(|(mail=%s)(proxyAddresses=smtp\3A%s))(!(objectclass=contact))(objectClass=person))

If you need to only skip Contacts and have AD groups returned, you can use the following Alias Query:
(&(|(mail=%s)(proxyAddresses=smtp\3A%s))(!(objectclass=contact)))