[healthnutter]

One trick is to use non-routable (e.g. 192.168.0.0/16) IP addresses with DNS records for subdomains of your company's domain name, e.g. devserver123.mycompany.com routes to 192.168.100.123

[bitJericho]

This gives insight to your internal network structure to the public. It's better to run a local DNS server for internal use.