Strange resolve for dig. Why?

Question

linux

And so the test call:
dig abc.com mx +short
5 cluster6.us.messagelabs.com.
20 cluster6a.us.messagelabs.com.
Abra-kadabra domain:
dig asdajsdkas.au mx +short
Response is null. Those. DNS said that the domain is bullshit, there is no such thing
. Another one:
dig asdajsdkas.com.au mx +short
The answer is similar to the one above.
dig jbsound.com.au mx +short
But this one calls
; <<>> DiG 9.10.3-P4-Ubuntu <<>> jbsound.com.au mx +short
;; global options: +cmd
;; connection timed out; no servers could be reached The
question is, why is this particular domain behaving this way?

Answer 1

Can't connect to NS servers of jbsound.com.au or .com.au or .au domain
. Nothing answers me.