Hi,
I'm setting up an ASA to use ISP failover. This method would appear to require the nat to the backup isp interface is not activated until the sla tracking indicates the primary isp is down.
I'm trying to discover if this email server failover shown below is correct approach for the isp failover setup.
Normally, there are two email servers with load balancing MX records (pref = 0) natted to the primary isp interface. If the primary isp goes down, they are natted to the backup interface, obviously a different network range.
From a MX record perspective, does this shown below work?
Pref Hostname IP address
-------------------------------------------
0 mail1.client.com a.b.c.d1
0 mail2.client.com a.b.c.d2
100 mail1.client.com w.x.y.z1
100 mail2.client.com w.x.y.z2
I've not implemented this previously and not sure if it works or what a best practice is within the contraints of an ASA isp failover setup.
Thanks.
