Microsoft Exchange Server Auth Certificate

Hi,

This is my third installation of Exchange 2013 server in the same forest but different Active Directory site /domain.

2 Exchange 2013 server are in one active directory site /domain i.e abc.xyz.com and this third server is in different AD site /domain i.e def.xyz.com.

To my surprise i am missing Microsoft Exchange Server Auth Certificate on this server.It is there on rest two exchange 2013 servers. 

I am getting below warning message in event log due to this:

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I am also getting one more error event which seems to be related to this:

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Any idea what went wrong here and how to resolve it now...?

Regards,

Vishal Malhan