[dns-operations] A strange DNS problem (intermittent SERVFAILs)

[Stephane Bortzmeyer]

On Sat, May 30, 2020 at 06:50:53PM +0000,
 dagon <dagon at sudo.sh> wrote 
 a message of 41 lines which said:

>      How can you even load
>      such a zone in a modern authority server?  All modern auth
>      servers would fail, I believe.

It may be that the authority server is correct but there is a firewall
in front of it, filtering requests and generating REFUSED, timeouts,
etc. I've seen people putting broken middleboxes before perfectly
working BIND servers...