[dns-operations] Observing DNS Propagation Inconsistencies Across Global Resolvers

[Vahid Shaik]

Hello,

I have been building and maintaining an open DNS propagation monitoring platform at DNS Robot (https://dnsrobot.net<https://dnsrobot.net/>) that queries 30+ globally distributed DNS resolvers simultaneously to track record propagation in real time.

During development and ongoing monitoring, I have observed some interesting inconsistencies in how different resolver implementations handle TTL expiry and cache refresh behavior. Specifically:

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.

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.

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.

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.

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.

Best regards,

Shaik Vahid

DNS Robot — https://dnsrobot.net<https://dnsrobot.net/>

Free DNS Propagation Checker & Network Tools
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