[dns-operations] PMTUD of .org servers

[Florian Weimer]

* Michael Graff:

> 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.

With UDP, it can also be implemented in the kernel.  It fragments down
to the path MTU when sending the packet.  This ensures that the number
of packets is minimized, so it's not entirely pointless.