The Change Auditor for Lync User Guide states the requirement of only installing a Change Auditor Agent on one Domain Controller:
"Deploy an agent on a domain controller - not the Lync Server"
The Change Auditor for Lync User Guide is incorrectly states that the Change Auditor agent only needs to be installed on one Domain Controller. Change Auditor agents are required to be installed on all Domain Controllers.
Enhancement request number TF600712 has been submitted to Development for consideration in a future release of Change Auditor to correct the Change Auditor for Lync User Guide.