root/boston.acme.com@ACME.COM

A principal associated with the root account on an NFS client. This is called a root principal and is needed for authenticated NFS-mounting to succeed.

host/boston.acme.com@ACME.COM

A principal used by the Kerberized applications (klist and kprop for example) and services (such as ftp and telnet). This is called a host or service principal.

username@ACME.COM

A principal for a user 

username/admin@ACME.COM

An admin principal that can be used to administer the KDC database

ftp/boston.acme.com@ACME.COM

A principal used by the ftp service. This can be used instead of a host principal.

K/M@ACME.COM

The master key name principal. There is one of these associated with each master KDC. 

kadmin/history@ACME.COM

A principal which includes a key used to keep password histories for other principals. There is one of these for each master KDC. 

kadmin/kdc1.acme.com@ACME.COM

A principal for the master KDC server that allows access to the KDC using kadmind

changepw/kdc1.acme.com@ACME.COM

A principal for the master KDC server that allows access to the KDC when changing passwords 

krbtgt/ACME.COM@ACME.COM

This principal is used when generating a ticket granting ticket.