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FAQ 59: Use for split DNSCategory: Everything else
Also referred to as split-horizon DNS, split-view DNS, or split-brain DNS.
Example: The server mail.example.com is located inside your LAN or in a DMZ, but your external DNS only answers with the external IP address.
You might need to answer with the internal/private IP so computers inside your LAN can reach the resource.
This is commonly accomplished by duplicating the entire DNS zone on an internal DNS server, or by using dns fixup commands on Cisco PIX/ASA firewalls.
Managing a separate DNS server internally or using different firewall hardware may be cost prohibitive, using DNS Redirector with the SimpleDNS=
function may be the alternative you're looking for.
You'll leave mail.example.com pointing to the external IP at your public/name servers, but declare mail.example.com to resolve to the inside IP in
Only this record will be manipulated when looked up through DNS Redirector, all other domain records will still be resolved by the external name server.