is the name of the service hosting the instance. For example, yourservicename.
Depending on the distribution you are using, the name of the service is defined either automatically by the server or manually by the user who created the service. For instance, CDH distributions automatically generate a service name, while Apache Hadoop distributions require that the service name be manually defined by the user. Refer to your distribution's documentation for additional information.
Fully_Qualified_Domain_Name
is the fully qualified domain name of the host machine. For example, yourserver.example.com.
REALM.COM
is the domain name of the host machine. This part of the value must be specified in upper-case characters. For example, EXAMPLE.COM.
Example
The following is an example of a valid service principal name:
If unspecified, the value of the ServerName property is used as the service principal name.