[dns-operations] Any DNAME usage experience?

John Levine johnl at taugh.com
Sun Mar 29 22:46:30 UTC 2020

In article <20200329204015.GK41308 at straasha.imrryr.org> you write:
>The actual user in question publishes TLSA RRs for only a selected
>subset of ports, e.g. for 25 and 443, but not 587.


>DNAME is a bit more flexible in this context.  It is by no means
>popular.  Among 1.87 million domains with DANE TLSA RRs for their
>primary MX hosts, 524 alias their TLSA RRs, of which three use DNAMEs
>that purpose.

Yeah, 89 of those CNAMEs are mine.

>And there are 2 TLDs that employ DNAMEs:
>    ; Taiwan simplified -> traditional
>    ;
>    xn--kprw13d. IN DNAME xn--kpry57d.
>    ; Iran arabic -> subdomain
>    xn--mgba3a4f16a. IN DNAME xn--mgba3a4f16a.ir.

>Bottom-line, they're used infrequently, but they do seem to work.

In the DNS sense, sure they work.

In the application sense, I doubt it.  When I looked through the .CAT
DNAMEs for www.<accented>.cat I don't think I found any web servers
that gave me what looked like a deliberate answer rather than a
default or error page.  I'd be quite surprised if there were many web
or mail servers in Taiwan or Iran that gave reasonable responses to
their DNAME'd names.


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