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<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
Hi dns-operators,</div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
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<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">I've recently noticed that 1.1.1.1 omits EDNS OPT RR in its response to certain queries, e.g.:</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
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<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">% dig @1.1.1.1 1.0.0.10.in-addr.arpa ptr +edns</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
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</div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">; <<>> DiG 9.18.20 <<>> @1.1.1.1 1.0.0.10.in-addr.arpa ptr +edns</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">; (1 server found)</span></div>
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<span class="elementToProof">;; global options: +cmd</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">;; Got answer:</span></div>
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<span class="elementToProof">;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 61776</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0</span></div>
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<br>
</div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">;; QUESTION SECTION:</span></div>
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<span class="elementToProof">;1.0.0.10.in-addr.arpa. IN PTR</span></div>
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</div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">;; Query time: 2 msec</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">;; WHEN: Thu Feb 19 22:51:21 PST 2026</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">;; MSG SIZE rcvd: 39</span></div>
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</div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">(It also omits SOA in the authority section). It includes OPT RR (and</span></div>
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<span class="elementToProof">SOA in the case of NXDOMAIN) for other cases like x.root-servers.net</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">(resulting in NXDOMAIN) or 4.0.41.198.in-addr.arpa/PTR.</span></div>
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<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">After trying various queries, it looks like this happens when the</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">query name is listed in RFC6303.</span></div>
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</div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">Is this a known behavior (I couldn't find any report on the net, thus</span></div>
<div style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<span class="elementToProof">asking here)? And, does anyone know the rationale of this behavior?</span></div>
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</div>
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<span class="elementToProof">Thanks,</span></div>
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</div>
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<span class="elementToProof">--</span></div>
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<span class="elementToProof">jinmei</span></div>
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