Ok so before I ask my questions, I'm going to briefly list how I've got things setup.
I've got 3 servers, all running MS Windows Server 2012 R2 Standard
2 of those servers, lets call them MAIL01 and MAIL02 have Exchange 2013 installed. Both the Mailbox and Client Access roles.
The other server is just the File Share Witness
I've created a DAG and have made MAIL01 and MAIL02 members of the DAG
I have a mailbox database on MAIL01 that I added a copy for on MAIL02
Lets assume I've got the following IP addresses on these
MAIL01 - 18.104.22.168
MAIL02 - 22.214.171.124
DAG - 126.96.36.199
I also have a Barracuda spam device setup lets assume IP 188.8.131.52
I am fully aware of how DAG and maintaining QUORUM works.
I am aware that DAG does not provide high availability to the CAS servers.
What I've done is on my domain controller in DNS, I've added 2 A host entries for mail.company.com pointing to 184.108.40.206 and 220.127.116.11. I implemented this because I don't have a hardware load balancer.
I have static NAT setup on my router for the following ports: 80, 110, 143, 443, 587, 993, 995. These all go to IP 18.104.22.168
I have 2 more ports, 25 and 465 which go to 22.214.171.124 which is the Barracuda. In the Barracuda config, I have it routing all e-mails to 126.96.36.199 which is the DAG.
I have a few questions based on this setup.
1. Is this properly setup for high availability?
2. I'm assuming that in order to provide the same kind of round robin DNS for the CAS server from the outside as I have from the inside, I'd need to have a public IP for each of the CAS servers and add both of those to my external DNS servers. If I do this, which ports would I need to setup static NAT for on my router?
3. Yesterday we had a short power outage which caused MAIL02 to go down. Once this happened, the database on MAIL01 was in a dismounted state and I was unable to mount it again. Things wouldn't start working again until MAIL02 was back online.
Basically what I'm trying to achieve is the following:
Have a single domain mail.company.com
Have multiple exchange servers for high availability so that if one were to go down, the other would still be available.
Continue to be able to use my Barracuda and have it route mails to a single IP address.
Any help with this would be much appreciated.