The mapping of host names onto realm names is defined in the domain_realm section of the krb5.conf file. These mappings can be defined for a whole domain and for individual hosts, depending on the requirements.
DNS can also be used to look up information about the KDCs. Using DNS makes it easier to change the information because you will not need to edit the krb5.conf file on all of the clients each time you make a change. See the krb5.conf(4) man page for more information.
As of the Solaris Express Developer Edition 1/08 and the Solaris 10 5/08 releases, Solaris Kerberos clients can interoperate better with Active Directory servers. The Active Directory servers can be configured to provide the realm to host mapping.