DNS and ISP redundancy
Posted on 2009-02-19
I have a firewall with 2 Internet interfaces. I have lets say ISP1 in interface 1 with IP of 126.96.36.199 and ISP2 in interface 2 with IP of 188.8.131.52. We run Outlook Web Access that needs to be up ALL the time. The firewall will automatically fail over to ISP2 if ISP1 is down. This works perfectly. The problem is DNS. The A record webmail points to 184.108.40.206. If this IP goes down and the other ISP is up, DNS has no way of knowing where to find Outlook Web Access. It will just come up page cannot be displayed. If a user types in 220.127.116.11 in this case, OWA will come up. Is there some kind of DNS failover like MX records have where if record 1 isn't available go to record 2?