1.1.1.1 omits EDNS OPT RR when serving "locally served zones"

[Tatsuya Jinmei]

Hi dns-operators,

I've recently noticed that 1.1.1.1 omits EDNS OPT RR in its response to certain queries, e.g.:

% dig @1.1.1.1 1.0.0.10.in-addr.arpa ptr +edns

; <<>> DiG 9.18.20 <<>> @1.1.1.1 1.0.0.10.in-addr.arpa ptr +edns
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 61776
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;1.0.0.10.in-addr.arpa.       IN    PTR

;; Query time: 2 msec
;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)
;; WHEN: Thu Feb 19 22:51:21 PST 2026
;; MSG SIZE  rcvd: 39

(It also omits SOA in the authority section). It includes OPT RR (and
SOA in the case of NXDOMAIN) for other cases like x.root-servers.net
(resulting in NXDOMAIN) or 4.0.41.198.in-addr.arpa/PTR.

After trying various queries, it looks like this happens when the
query name is listed in RFC6303.

Is this a known behavior (I couldn't find any report on the net, thus
asking here)? And, does anyone know the rationale of this behavior?

Thanks,

--
jinmei
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