The LDAP module provides different features depending on which of the three possible validation modes is implemented.
With Replication Mode, data from LDAP is replicated into the Sitecore Security (or Extranet) database. Replication can be scheduled or performed manually by an administrator.
In Live Validation Mode, only groups are copied from the directory to Sitecore.
Mixed Validation Mode functions as a combination of Live and Replication modes
Features Summary Table