Extending The Schema; Schema Checking - Red Hat DIRECTORY SERVER 8.1 - SCHEMA Reference

of numeric OIDs can lead to problems with clients, server interoperability, and server
behavior, assigning a numeric OID is strongly recommended.
OIDs can be built on. The base OID is a root number which is used for every schema element for an
organization, and then schema elements can be incremented from there. For example, a base OID
could be 1. The company then uses 1.1 for attributes, so every new attribute has an OID of 1.1.x. It
uses 1.2 for object classes, so every new object class has an OID of 1.2.x.
For Directory Server-defined schema elements, the base OIDs are as follows:
• The Netscape base OID is 2.16.840.1.113730.
• The Directory Server base OID is 2.16.840.1.113730.3.
• All Netscape-defined attributes have the base OID 2.16.840.1.113370.3.1.
• All Netscape-defined object classes have the base OID 2.16.840.1.113730.3.2.
For more information about OIDs or to request a prefix, go to the Internet Assigned Number Authority
(IANA) website at http://www.iana.org/.

1.4. Extending the Schema

The Directory Server schema includes hundreds of object classes and attributes that can be used
to meet most of directory requirements. This schema can be extended with new object classes and
attributes that meet evolving requirements for the directory service in the enterprise by creating
custom schema files.
When adding new attributes to the schema, a new object class should be created to contain them.
Adding a new attribute to an existing object class can compromise the Directory Server's compatibility
with existing LDAP clients that rely on the standard LDAP schema and may cause difficulties when
upgrading the server.
For more information about extending server schema, see the Deployment Guide.

1.5. Schema Checking

Schema checking means that the Directory Server checks every entry when it is created, modified,
or in a database imported using LDIF to make sure that it complies with the schema definitions in the
schema files. Schema checking verifies three things:
• Object classes and attributes used in the entry are defined in the directory schema.
• Attributes required for an object class are contained in the entry.
• Only attributes allowed by the object class are contained in the entry.
You should run Directory Server with schema checking turned on. For information on enabling schema
checking, see the Administrator's Guide.
Extending the Schema
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