BIND 8.something broke support for having a CNAME at the top of a zone, which was used widely. Supposedly, the RFCs never supported this “feature” and ISC decided to fix the “bug”, recommending an alternative: SRV RRs.

SRV RRs provide a better mechanism for specifying target hostnames (and ports!) for various services, however they remain unsupported by pretty much everything.

Some fun quotes on the subject:

“isc remains deeply apologetic that prior versions of BIND did not properly catch the configuration error that you appear to have built your business on. however, there are workarounds, and i suggest that rather than wasting more of your time and our time arguing about it, you get to work on implementing one.”
— Paul A Vixie

“Eric, why do you want a CNAME at the top of zone? Is it because you have a another party hosting your HTTP service? There is DNS resource record specifically for supporting this sort of thing, it is called SRV which provides a generalised form of the MX record. It has been around since 1996.
“Now you will find it much easier to update all the http clients in the world than it will be to update all the DNS servers in the world. For one thing, people are used to updating HTTP clients. Secondly it is a better solution.
“… Complain to Netscape, Microsoft etc. saying that you want SRV support in the browsers, ftp client etc.”

“This whole discussion s truly absurd.   You clearly have no idea what the intent of CNAMES was.”
— Erik Aronesty


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