As an LDAP firewall and proxy, a virtual directory can basically provide DLP (data leakage protection) which works by publishing only the data required and searched for by the application. Your Active Directory is made more secure, safe and protection with inefficient queries being transformed in real time making them more efficient. The complete auditing solution for every application which accessed the Active Directory including activities like searches and changes are caught is also something that a virtual directory server can provide when it is used otherwise as LDAP firewall and proxy.