[dns-operations] PMTUD of .org servers

Michael Graff mgraff at isc.org
Sat Jun 20 13:34:07 UTC 2009

Pmtu requires that the thing sending data use the pmtu feedback. With  
tcp this happens in the kernel. With UDP it happens in the application.

Do any servers actually ask the os for this feedback or process the  
icmp messages?


On Jun 20, 2009, at 8:29, Florian Weimer <fw at deneb.enyo.de> wrote:

> * Mark Andrews:
>> In message <87r5xf9id8.fsf at mid.deneb.enyo.de>, Florian Weimer writes:
>>> * Mark Andrews:
>>>>    Path MTU discover is just a waste of resources for DNS/UDP.
>>> Most authoritative server operators seem to disagree.
>> Please list one that deliberately turned it on for UDP.
> How would I know?  There's no "DF and I really mean it" bit.
> I expect that an operator high enough up the tree would know about
> PMTUD, and that the server configuration reflects operator choice.
> And it's something that ICANN's SSAC likely has covered (especially
> when AAAA records were added to the priming response).
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