Hi @Topf, Jonathan ,
From the documentation: Active Directory Domain Services support in Lync Server 2013, the minimum Domain Functional Level / Forest Functional Level is 2003.
The minumum domain functional level for introducing the first 2016 domain controller is also 2003.
It is not officially known whether it will work or not, because there are no documentations or claims for this, this usually means that Microsoft probably have not tested this scenario.
From some of my customer experience it has worked just fine.
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Best regards,
Leon