Directory servers expose their capabilities, suffixes they support, and so forth as attribute values on the root DSE. See the section on Reading Root DSEs.
This allows your application to discover a variety of information at run time, rather than storing configuration separately. Thus putting effort into querying the directory about its configuration and the features it supports can make your application easier to deploy and to maintain.
For example, rather than hard-coding
dc=example,dc=com
as a suffix DN in your configuration,
you can search the root DSE on OpenDJ for namingContexts
,
and then search under the naming context DNs to locate the entries you are
looking for in order to initialize your configuration.
Directory servers also expose their schema over LDAP. The root DSE
attribute subschemaSubentry
shows the DN of the entry
holding LDAP schema definitions. See the section, Getting Schema
Information. Note that LDAP object class and attribute
type names are case-insensitive, so isMemberOf
and
ismemberof
refer to the same attribute for example.