Create a single record internally for an external zone

Q. I need to create a DNS record internally for an external zone but don't want to clash the entire DNS zone. What can I do?

A. It's very common that a DNS name should resolve differently within an organization than from the Internet. For example you may want www..com to resolve to one site on the Internet but a different site on the company Intranet. One solution would be to create a DNS zone .com on your Intranet DNS server which could also have a www record pointing to your internal site however if users tried to resolve other DNS names for .com it would fail since the records would not be present. Another approach instead of creating a zone for the domain name is to create a zone just for the record you want, for example www..com which may seem strange but within that zone you then create an A record with no name (so it uses the parent zone name) then the IP you want to resolve to.

In my example below I wanted www.savilltech.com to resolve to an internal host on my network but still enable other savilltech.com names to resolve. As can be seen I added a zone named www.savilltech.com then in the zone create a host record (A) with no name that then resolves to the desired IP. If any other savilltech.com name is used internally there is no matching zone on the internal DNS and it will resolve to the Internet DNS hosting savilltech.com.

The same approach can also be useful for ADFS server names etc that should resolve differently on the Internet and internally.

Each week, John Savill answers all of your toughest tech questions about the worlds of Windows Server, Azure, and beyond. Read his past IT advice here, and email your questions to john@savilltech.com.

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