We use MIIS for galsync.

How the legacyExchangeDN of contacts is determined by MIIS galsync ?

It depends on provisioning implementation ?

blackjack,

The legacyExchangeDN value is not determined by GALSYNC...........Exchange actually supplies this value. If using Exchange 2003, then the RUS (recipient update service) runs all the time and is responsible for that. If using 2007/2010/2013, then this needs to be invoked when making objects programmatically, the way MIIS/ILM/FIM does. ILM FP1/FIM use a powershell cmdlet (which actually is part of Exchange) called 'update-recipient' that performs this functionality. If you are seeing contacts provisioned but they aren't in the GAL and lack this attribute, then you either are using version of sync engine before ILM 2007 FP1 or you are not using 'Exchange provisioning' (configured on the 'configure extensions' property page of the GALSYNC MA) checkbox.