Methodology
How geographic DNS comparison works
Global DNS Lookup is designed to answer a focused diagnostic question: could the same hostname resolve differently when a DNS provider considers users from different countries? The tool compares A, AAAA and CNAME responses for a set of representative network prefixes. It does not claim to reproduce every ISP, device or resolver cache inside a country.
DNS-over-HTTPS queries
The browser sends DNS-over-HTTPS requests to supported public resolvers. DNS-over-HTTPS carries a normal DNS question through HTTPS, allowing the application to request structured DNS data without operating its own recursive DNS server. The response is parsed into CNAME, IPv4 and IPv6 records and includes available TTL values.
Google Public DNS is normally queried first. AliDNS is preferred for the China Mainland comparison, and either provider may be used as a fallback after a network or provider failure. Each result identifies the resolver that supplied it so a fallback is not mistaken for an answer from the preferred provider.
Representative EDNS Client Subnet prefixes
Some authoritative DNS and CDN systems use EDNS Client Subnet, commonly abbreviated ECS, to tailor an answer for part of a user's network. For each listed location, the tool supplies a configured public network prefix associated with that country. The prefix is a diagnostic hint; it is not your IP address and does not identify a specific visitor.
Resolver and authoritative-server behavior varies. A resolver can reduce the prefix length, ignore ECS, answer from cache or apply its own privacy policy. Consequently, identical answers across all rows do not prove that every network receives the same result, and different answers do not by themselves prove a fault.
How records are interpreted
- CNAME: shows aliases followed before reaching address records.
- A: lists IPv4 endpoints returned for the requested hostname.
- AAAA: lists IPv6 endpoints, when the hostname publishes them.
- TTL: reports the cache lifetime supplied with each parsed record.
- Status: distinguishes success, partial data, NXDOMAIN and provider failure.
A missing record type is not always an error. Many valid services publish A records without AAAA records. NXDOMAIN means the DNS response says the name does not exist, while a failed request indicates that the tool could not obtain a usable response from its providers.
Common reasons for regional differences
CDNs commonly return nearby edge addresses to reduce latency. Global traffic managers may direct users away from an unhealthy region, separate regulated environments, or stage a rollout country by country. Differences can also persist temporarily because recursive resolvers cache records until their TTL expires.
When investigating a change, compare the CNAME chain and address records separately. A new CNAME can indicate that traffic moved to another platform, while an unchanged CNAME with new addresses may simply reflect normal CDN routing. Check both IPv4 and IPv6 because the two paths can be configured independently.
Limitations and responsible use
This is a DNS comparison, not an uptime, latency, HTTP, TLS or security test. It does not connect to the returned addresses and cannot verify whether a website works from a country. Corporate split-horizon DNS, private zones and names that only resolve inside a private network are outside the intended use of this public tool.
Avoid entering confidential internal hostnames. For a production incident, confirm important findings with the authoritative DNS configuration, the affected ISP or a trusted physical probe in the region. The comparison is most useful for identifying where to investigate next, not as the only source of truth.