login.authorize.net has A and CNAME records
marka at isc.org
Wed Apr 7 07:32:56 UTC 2021
> On 7 Apr 2021, at 17:20, Bjørn Mork <bjorn at mork.no> wrote:
> Bjørn Mork <bjorn at mork.no> writes:
>> Seth Mattinen <sethm at rollernet.us> writes:
>>> On 4/6/21 11:35 AM, Arne Jensen wrote:
>>>> login.authorize.net. is a CNAME, but does not have any A records itself.
>>> This one returns A records:
>> Looks like they host DNS on both cloudflare and akami, but zone contents
>> are different on the two platforms:
>> bjorn at miraculix:~$ for s in $(dig +short ns authorize.net|sort); do echo -n "$s: ";dig +short login.authorize.net @$s|xargs; done
>> a10-64.akam.net.: login.authorize.net.cdn.cloudflare.net.
>> a1-190.akam.net.: login.authorize.net.cdn.cloudflare.net.
>> a2-65.akam.net.: login.authorize.net.cdn.cloudflare.net.
>> a9-64.akam.net.: login.authorize.net.cdn.cloudflare.net.
>> ns0090.secondary.cloudflare.com.: 126.96.36.199 188.8.131.52
>> ns0210.secondary.cloudflare.com.: 184.108.40.206 220.127.116.11
> Doh! I should know better. Sorry, ignore that. Don't ask for A records
> if you want to see CNAMEs..
It shouldn’t matter. Only non-rfc-compliant servers allow A and CNAME
to co-exist at the same name. That combination was prohibited by RFC
"The domain system provides such a feature using the canonical name
(CNAME) RR. A CNAME RR identifies its owner name as an alias, and
specifies the corresponding canonical name in the RDATA section of the
RR. If a CNAME RR is present at a node, no other data should be
present; this ensures that the data for a canonical name and its aliases
cannot be different. This rule also insures that a cached CNAME can be
used without checking with an authoritative server for other RR types.”
Returning a signed CNAME is cryptographic proof that an A record does not
exist at the name with DNSSEC.
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka at isc.org
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