Re: [mydns-users] base rr as a CNAME
Status: Beta
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From: David P. <da...@ac...> - 2002-11-08 22:27:37
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Allen Bettilyon writes: > My question is simply, Is this valid? Will there be any problems with > other resolvers doing it this way? Or do I need to have specific NS > records for zone.com? No, it is not valid. Section 3.6.2 of RFC 1034 says that ``Domain names in RRs which point at another name should always point at the primary name and not the alias. This avoids extra indirections in accessing information.'' See the ``Aliases'' section of this page: http://cr.yp.to/djbdns/notes.html It will work with some resolvers but is not valid and thus not guaranteed to work with all resolvers. In general, you should avoid CNAMEs. As Dan Bernstein says, ``DNS should have been designed without aliases.'' It is very easy to avoid aliases with MyDNS. Either code around them in your application or use my aliases patch, which provides true server side aliases. MyDNS has the nice feature of automatically returning the A records for CNAMEs for which it is authoritative, which in some cases will avoid extra DNS traffic. However, it still doesn't fully solve the problem. Aliases should be done server side, not client side. CNAMEs must not be used for MX records. This is another good reason to entirely avoid CNAME records: http://cr.yp.to/im/cname.html If anyone is interested, I will update my aliases patch for 0.9.5 when it comes out. Unless, of course, Don would like to send me a pre-release so I can update it beforehand :) -- David Phillips <da...@ac...> http://david.acz.org/ |