Are there cost effective ways to do load balancing for SMBs?
Specifically.. consider an SMB with Microsoft Exchange. The SMB has multiple ISP's for redundancy (we will say cable and DSL for this example).
So all email flows as well as OWA access over the cable internet. Should the cable internet connection be disrupted, services fail over to using the DSL. The firewall is already configured to handle this from a communication standpoint. And the MX records are configured for both connections with different MX priorities so mail flow works fine.
What is the best way to handle the DNS change/failover for mail.company.com once it fails over to the DSL?
We have looked at some appliances like the Barracuda Load Balancer but they are not cheap. (I know it is all relative). Outside of using dynamic DNS, are there any other cost-effective ways to accomplish this?