round robin fails with two record RRSET in 9.12.1-P2 on rDNS
Summary
An RRSET with two A records fails to properly round-robin for recursive servers running 9.12.1-P2. It works fine on the authoritative servers, and it works on the rDNS server if there are three or more records.
Steps to reproduce
dig roundrobin.ucsc.edu @adns2.ucsc.edu
In theory, your rDNS server running 9.12.1-P2 will not show proper round-robin behavior on that query. Our rDNS servers are also authoritative for ucsc.edu, but the same behavior manifests when I query something for which our rDNS is not authoritative:
dig www.yale.edu.cdn.cloudflare.net
so I believe this issue should be easily seen by anyone running 9.12.1-P2 for rDNS.
What is the current bug behavior?
The pair of records are always returned in the same order.
What is the expected correct behavior?
Records returned round robin.
Relevant configuration files
I am going to poke in only a few config lines on the theory that the general config is probably not relevant. I'm happy to flogged if I get that wrong and will provide full details if needed.
rrset-order { order cyclic; }; recursion yes; dnssec-enable yes; dnssec-validation yes; response-policy { .... }