Today I had the issue on a customer site that the DirSync document showed up the following error:

DirSync: Directory Assistance LDAP host is an unsupported load balancing sprayer. Change it to a dedicated host name and create a Resync request.

After opening a case I received the information that this is a well known error ( https://support.hcl-software.com/csm?id=kb_article&sysparm_article=KB0104047 ) and it can be resolved by adding the following NOTES.INI entry on the Domino Server which is responsible for the DirSync:

DIRSYNC_ALLOW_HOST_SPRAYERS=1

After adding this entry the Directory Sync is running fine and the DirSync document again shows “No error”.