[dns-operations] Cloudflare people here ? Problematic records served from a Cloudflare hosted zone.

[Winfried]

Hi,

On 11/21/25 11:41, Emmanuel Fusté wrote:
> Hi Joe,
>
> Le 20/11/2025 à 19:07, Joe Abley a écrit :
>> Hi Emmanuel,
>>
>> On 20 Nov 2025, at 16:53, Emmanuel Fusté <manu.fuste at gmail.com> wrote:
>>
>>> With a colleague we found by accident read world records served by 
>>> Cloudflare DNS which are breaking the DNS data model: multiple 
>>> possible CNAME values for a same record leading to possible 
>>> resolver's cache pollution.
>>> As the way to get one value or another is trivial, the way to 
>>> control the resolver cached value is trivial too.
>>> We did not find how Cloudflare DNS features and zone content where 
>>> used/combined to generate this behavior which is surely unexpected 
>>> for the zone operator.
>>> Is there some Cloudflare people here to whom I could provide the 
>>> zone/records details to see if it is an expected/assumed behavior or 
>>> a subtle corner case bug ?
>> There are a few of us here. Feel free to ping me off-list!
>>
>>
>> Joe
> Thank you ! Details transmited off-list.

Please keep us informed if this case could cause problems for other 
resolver operators as well or is otherwise relevant to them.

Winfried
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