Global DNS Propagation Checker

Introduction:

Domain Name System (DNS) propagation describes the time lag between publishing a new or updated resource-record set and that information becoming reachable to recursive resolvers everywhere. Because each resolver caches answers for its configured Time-to-Live, users in different regions may receive different results until every cache ages out or refreshes.

The Global DNS Propagation Checker queries multiple independent public resolvers simultaneously through DNS-over-HTTPS, tallies their returned values, then calculates the percentage that matches the most common answer. It presents that percentage, the answer distribution, and the complete raw data in tabular, graphical, and machine-readable formats.

Run the checker during record migrations, e-mail host changes, or content-delivery switch-overs to confirm that visitors now resolve the intended address. *Remember that private enterprise resolvers or region-blocked services may still diverge despite public propagation.*

Technical Details:

DNS propagation monitoring hinges on sampling authoritative answers returned by globally dispersed recursive resolvers. Each resolver’s response reflects its current cache state, which depends on Time-to-Live expiration, negative caching rules, and local policy. By comparing answer homogeneity across providers, administrators infer whether a new record has achieved universal visibility, guiding cut-over timing and rollback decisions.

1. Dispatch DNS-over-HTTPS queries for the domain and resource-record type to a curated resolver list.
2. Collect each resolver’s answer string; substitute ‘—’ for network or format failures.
3. Identify majority answer — the most frequent non-failure string.
4. Count propagated k — resolvers whose answer equals the majority.
5. Compute propagation percentage.

A fully propagated state suggests that end-users worldwide now resolve the new record; partial states warrant continued monitoring.

• Queries use DNS-over-HTTPS; resolver choice may bias geographic coverage.
• Majority answer assumes correctness; a widespread misconfiguration can falsely appear propagated.
• Tool does not inspect authoritative name-server logs.
• Network firewalls or DoH blocking may reduce sample size.

• Mixed IPv4/IPv6 answers for A and AAAA records.
• Wildcard records obscuring precise propagation state.
• Split-horizon DNS where public resolvers intentionally disagree.
• Resolver rate-limiting returning HTTP 429 responses.

Concepts align with IETF RFC 1034 and RFC 1035, which formalise DNS behaviour, caching, and negative responses. RFC 8484 defines DNS-over-HTTPS transport employed here. Empirical measurement techniques reflect common operational practices documented by regional network operator groups.

This method transmits the queried domain name to selected public resolvers and therefore falls under GDPR Article 4 definitions of potentially personal network data.

Step-by-Step Guide:

Follow these steps to check whether your new or updated record has propagated:

1. Enter the target Domain in fully qualified form.
2. Select the desired Record Type from the drop-down.
3. Click Check to send simultaneous queries to public resolvers.
4. Review the propagation percentage and answer distribution.
5. If the result is partial, wait the original TTL before retesting.

FAQ:

Glossary:

DNS

System mapping names to resource records.

Resolver

Recursive server answering client queries.

TTL

Cache lifetime for a record, in seconds.

DNS-over-HTTPS

Transport that tunnels DNS traffic inside HTTPS.

Propagation %

Share of resolvers returning the majority answer.