How todo a LoadBalancer of traffic to internal hosts ?

Hello everybody,

My deal is to do a “Load Balancing/FailOver/NBL Cluster” mechanism who will be redirect traffic push from ONE public IP to two internal hosts in LAN dependence what’s internal host is alive.
I hope this question is understanding.
Core situation is to push e-mails to that internal MTA hosts who is alive, they are replicate together e-mails boxes.

I thinking about:

  • Two DNAT rules whom will be enable/disable by monitoring internal host script.
  • Maybe NTH action can work like this.
  • Routing with separate mark packet/connection and two routing table is for me to insane/mad idea and I think not work for internal hosts.

Please help me with this case.
I will be doing testing on virtual MT demo.

Maybe some of you have like this situation in your network?

Best Regards
SiB