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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">Hello,</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">I have been building and maintaining an open DNS propagation monitoring platform at DNS Robot (</span><span style="font-family: Aptos; font-size: 12pt; color: rgb(153, 0, 250);"><a href="https://dnsrobot.net/" target="_blank" title="https://dnsrobot.net/" rel="noopener noreferrer nofollow" data-outlook-id="5d8c65c0-7a90-4b14-83d7-37a12577c764" style="color: rgb(153, 0, 250); margin-top: 0px; margin-bottom: 0px;">https://dnsrobot.net</a></span><span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">)
that queries 30+ globally distributed DNS resolvers simultaneously to track record propagation in real time.</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">During development and ongoing monitoring, I have observed some interesting inconsistencies in how different resolver implementations handle TTL expiry and cache refresh behavior. Specifically:</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">1. Some major public resolvers (particularly in Asia-Pacific regions) appear to serve stale records well beyond the configured TTL, sometimes by 2-3x the expected duration.</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">2. DNSSEC-signed zones occasionally show inconsistent DS record propagation between parent and child zones during key rollovers, visible when checking multiple resolvers within a short
window.</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">3. CNAME flattening behavior varies significantly — some resolvers return the flattened A record while others return the CNAME chain, which can cause confusion when debugging propagation.</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">These observations come from real-time queries across resolvers in 20+ countries. I am curious whether others on this list have documented similar patterns, or if there are known resolver-specific
behaviours that explain these discrepancies.</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(33, 33, 33);">I would also welcome any feedback on best practices for measuring propagation completeness — specifically, what threshold of global resolver agreement should be considered "fully propagated” for
operational purposes.</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">Best regards,</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">Shaik Vahid</span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">DNS Robot —
</span><span style="font-family: Aptos; font-size: 12pt; color: rgb(153, 0, 250);"><a href="https://dnsrobot.net/" target="_blank" title="https://dnsrobot.net/" rel="noopener noreferrer nofollow" data-outlook-id="a23678c0-617c-4f7f-a6a3-170dbe82d91b" style="color: rgb(153, 0, 250); margin-top: 0px; margin-bottom: 0px;">https://dnsrobot.net</a></span></p>
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<span style="font-family: Aptos; font-size: 12pt; color: rgb(0, 0, 0);">Free DNS Propagation Checker & Network Tools</span></p>
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