# Configuring schema files on external directory servers

A schema file defines the attributes (individual pieces of data) that an account can contain.

Updating the external server’s schema with SMC-specific attributes is optional. Updating the schema also allows you to add SMC-specific information to Users and User Groups through the SMC Client.

You must update the schema file in the following cases:

- To be able to configure authentication requirements for specific Users or User Groups. Otherwise, you can configure authentication only at the LDAP domain level.
- To use the User password authentication method to authenticate users using user names and passwords.

  Alternatively, you can use the LDAP Authentication authentication method to authenticate users using user names and passwords without updating the schema.

- To be able to edit information in the LDAP directory through the SMC Client.

The method of configuring Schema files varies depending on which LDAP server you are using. The Schema update is done outside the SMC Client. In general, the schema update means that you add the SMC-specific attributes to the existing user information on the external LDAP server. These include attributes for the SMC-specific user name, password, and allowed authentication methods for the user.