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

[T.Suzuki]

Hello.

You're doing a good job.
But please don't say "Propagation". 
Please also provide proper guidance for readers.

The reason is as follows: https://www.e-ontap.com/dns/propagation/harmful-e.html

On Mon, 2 Mar 2026 17:12:38 +0000
Vahid Shaik <vahid at dnsrobot.net> wrote:

> 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

-- 
T.Suzuki