In Exchange you have the ability to add 'External DNS' addresses. Ours has always had our ISP's DNS records set.
After reading several questions on this site, most people are saying you shouldn't use this option and leave it blank.
The system, which Exchange runs on, has it's own static IP and the DNS records point solely to our internal DNS servers both at 192.168.1.10 & 11.
These DNS servers have forwarders set to our ISP's DNS Servers. Everything works OK.
Is it, therefore, best to have no IP addresses in the 'External DNS' settings within Exchange or to additionally add our Internal DNS Servers?