The mapping of host names to 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.
You can also use DNS to look up information about the KDCs. Using DNS makes changing the information easier because you do not need to edit the krb5.conf file on all Kerberos clients for each change.
For more information, see the krb5.conf(4) man page.
Kerberos clients in Oracle Solaris interoperate well with Active Directory servers. The Active Directory servers can be configured to provide the realm to host mapping.