If we're looking for more counterexamples, there's also RFC7873#5.4
For servers with DNS Cookies enabled, the QUERY opcode behavior is
extended to support queries with an empty Question Section (a QDCOUNT
of zero (0)), provided that an OPT record is present with a COOKIE
option. Such servers will send a reply that has an empty
Answer Section and has a COOKIE option containing the Client Cookie
and a valid Server Cookie.
I can see why that was added, but I really wish it hadn't been...
Ray
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