Exchange database is mounting on DR site instead of Production site

I have three exchange mailbox server 2010 in DAG. Two mailbox server is in A location and one mailbox server is in B location.Database is active on a server of A location. But whenever an exchange server has problem, database gets mount on B location instead of second mailbox server of A location. For example

A location has below servers....
Exchange1 and Exchange2

B location has below servers

If Exchange1 gets down databases should auto get mount on Exchange2 but this is not happening. If Exchange1 has problem then DB is mounting on Exchange3 instead of Exchange2. Same is happening for exchange2 also. Thank you.
Arif KhanSystem AdministratorAsked:
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Jason MIT Systems AdministratorCommented:
How is your node majority configured?

Take a look at this link -
When you say DR site I would consider two different site .

Where is your PAM? Check if you have enable the DAC node
Peter HutchisonSenior Network Systems SpecialistCommented:
Check the database copy activation preference, the preference determine which database server to mount the database on next, if the first primary database server has problems. You can view the preferences in the Exchange Management Console, Mailbox, Database Management.
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Arif KhanSystem AdministratorAuthor Commented:
Hi Pradip,

Yes I have two site. Once is A location and other is B location. My Active mailbox server is in A location and one more passive server here having healthy copy. One passive is in B location having healthy copy.

Hi Peter,
Preference is set right but it does not work as per preference.
Where is your PAM and have you configured the DAC mode
Arif KhanSystem AdministratorAuthor Commented:
PAM is in A location and DAC mode is Off
Enable the DAC mode and check

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Arif KhanSystem AdministratorAuthor Commented:
Ok, I will check enable it.
Arif KhanSystem AdministratorAuthor Commented:
I have enabled it. How can I test it?. If I restart it, then whole database will mount on other server and again management will ask me to find the root cause. Is there any way to test on single DB?

Used below command to enable DAC

Set-DatabaseAvailabilityGroup EX2016DAG01 -DatacenterActivationMode DagOnly
Just activate the copy on the primary site which is activated on DR site and check the behaviour
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