Create/Join with Reject on Match is not finding objects on peer domains

A typical Create/Join (Sync/Join Mode set to Both) can only search the root domain of the Destination DC.

dc=root,dc=com

Peer domains are not detected by default, so using Create/Join for your Sync Mode with Reject on Match will not see anything in the other root peer domain. Therefore, an undesirable Add is performed because Reject on Match cannot reject an object it cannot see - which it can’t if it cannot detect a peer domain object.

dc=Theroot (root domain)
dc=otherroot2
dc=otherroot3

As of UnitySync v2.5 there is a new option on the Destination tab - Optional SearchModeBase=NULL.

With a null SearchModeBase, the Create/Join will see Destination peer domains. Reject on Match will successfully trigger on objects found in the peer domains and therefore duplicate objects will not be created.

Note: The sync cannot write to the peer domain objects. It can only search them as necessary to allow them to be rejected by Reject on Match for a Create/Join.