If your network uses multiple LDAP/AD servers with referrals, then select one as the primary server (probably the one that holds the bulk of the users) and use the above settings for that server. It then refers the SonicWall on to the other servers for users in domains other than its own. For the SonicWall to be able to log in to those other servers, each server must have a user configured with the same credentials (user name, password and location in the directory) as per the login to primary server. This might entail creating a special user in the directory for the SonicWall login. Note that only read access to the directory is required.
The LDAP Configuration page is displayed.
Click Referrals tab.
Select the following:
Allow referrals
Allow continuation references during user authentication
Allow continuation references during directory auto-configuration
Allow continuation references in domain searches
Click Apply.