And this definition:
When deciding on suffixes, where a suffix is the root DN of a directory tree, it is a good idea to use the same naming structure for LDAP as is used for X.500. Using the X.500 methodology would lead to choosing a suffix like o=ibm,c=us or ou=raleigh,o=ibm.
This method will set the root of the directory tree to a specific organization in a specific country or to a specific organization and organizational unit. However, it is not necessary to do this, unless there are plans to participate in an X.500 directory service, since LDAP does not require any specific format for the DN naming convention. In LDAP, the directory suffix can be chosen freely to reflect the organizations distinct name. Another method that you can use, if the X.500 method does not seem appropriate, is the DNS naming model when choosing the directory suffix. This would result in a suffix using the domainComponent attribute, for example, dc=server,dc=company,dc=com.