Hi We have an Exchange Server 2013 environment which is deployed on 2 Sites.

Site A and Site B. Both Sites are connected via VPN.

We have 2 mailbox servers on each site. We have create a DAG all 4 mailbox server are member of that DAG. We have a third site which is on separate location and this site is also connected via vpn with both Sites as shown in the diagram.

The issue is that our databases were mounted on Mailbox 1 on Site A. Primary active manager was also on Mailbox A. VPN from site B to Site A was disconnected. Due to this our databases were dismounted and users faced disconnectivity. We were able to access Site B from  Site A but Single Site VPN tunnel was disconnected from Site B to Site A. Can anyone help us why our databases were dismounted.

In case our VPN tunnel from Third Site to Site A disconnects then how we can able to failover to Site B. We have DNS failover and if any of our CAS is not accessible then DNS automatically failover to next CAS server and OWA points to active CAS but our DAG does not failover. Can any body give us any opinion.

Any help will be highly appreciated.

Regards,

Anees

• Edited by AneesUrRehman 15 hours 44 minutes ago correction

Are you sure that the VPN failure wasn't caused by a network event that also caused a disconnection to Third Site?  In that case you would lose quorum.

Also, consider whether a VPN tunnel is robust enough for you to depend on it for a stretche