I have a question regarding ISP redundancy and DNS records for Web Servers behind my firewall.
Lets say I have a R80.30 Cluster XL with one ISP. I have a reverse proxy in my dmz which services stuff like webmail and some webservers. Each service has a unique public IP which is resolvable via A record for my domain from my externally configured DNS Servers. DNS looks like follows:
mydomain.com. 1800 IN NS ns1.dnsprovider.com
mydomain.com. 1800 IN NS ns2.dnsprovider.com
webmail.mydomain.com 1800 IN A 184.108.40.206 (sorry cloudflare, this is just an example)
webserver.mydomain.com 1800 IN A 220.127.116.11 (see above)
If I add a second ISP, how can I make sure that in case of failure of ISP 1 my web-services are still reachable? The documentation for ISP redundancy and DNS proxy is not clear to me.
Do I have to point my domains name servers to my two public ip addresses of my firewalls now so that the DNS proxy can resolve the correct external IP during failover (so change ns1.dnsprovider.com to the public external IP of my firewall)?
What happens for non-A-records? Do I have to configure the external DNS provider for the firewall to forward the traffic to?
Thanks for your help 😉