[dns-operations] Any DNAME usage experience?

Tony Finch dot at dotat.at
Mon Mar 30 11:33:59 UTC 2020

Meir Kraushar via dns-operations <dns-operations at dns-oarc.net> wrote:
> I looking for insights, usage experience regarding DNAME record
> implementation. If any compatibility issues, client side problems,
> resolvers etc?.. Highly apperciate If anyone could share their
> knowledge.

At Cambridge University we're using DNAMEs for classless reverse DNS
delegation for shorter prefixes, originally to minimize the number of
zones when was delegated, and more recently to handle the
way we split for departments and for the
University as a whole.


It works OK except that we had problems with a mail server: some recipient
sites had buggy mailers that could not understand DNAMEs in the reverse
DNS so rejected mail. The problem was fixed by changing the mail server's
/24 to use a forest of CNAMEs instead of a DNAME.

I had wondered if DNAME support had improved enough in the last 10 years
to make this workaround unnecessary, but sadly it sounds like there are
still too many buggy resolvers :-(

There was also some annoyance with the glibc resolver: it would chatter
into syslog about unexpected records (i.e. DNAMEs) when parsing DNS
responses. This was fixed years ago.

f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
Ardnamurchan Point to Cape Wrath: North or northwest, backing west or
northwest, 4 or 5. Moderate occasionally rough in north. Showers. Good.

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