DNS 比較ツール

このツールについて

When you update a DNS record, different resolvers pick up the change at different times because each caches the old value for its own TTL (Time To Live) period. This tool queries Google Public DNS and Cloudflare DNS at the same time and shows both answers side by side, flagging whether they agree or disagree—useful right after changing a record to see if it has started propagating. Note that this checks two independent public resolver providers, not geographic regions: both queries originate from your current network location, so it cannot confirm whether a change has reached every region worldwide the way a dedicated multi-location propagation checker can.

使い方

1. 1Type a domain name and choose a record type (A, AAAA, CNAME, MX, NS, or TXT).
2. 2Click "Compare" — Google Public DNS and Cloudflare DNS are queried at the same time.
3. 3A green banner means both resolvers returned the same records; an orange banner means they disagree.
4. 4If one resolver still shows the old value, its cached copy of the record has not expired yet—wait out the record's TTL and check again.

よくある質問 (FAQ)

Does this check DNS propagation worldwide?

Not geographically. It compares what two different DNS resolver providers (Google and Cloudflare) currently know, both queried from your own network location. A true worldwide propagation checker probes from many physical locations around the globe, which requires server infrastructure this browser-only tool does not have.

Why would Google and Cloudflare show different results?

Each resolver maintains its own cache. If you recently changed a record, whichever resolver queried your domain more recently will have the fresh value, while the other may still be serving a cached copy until its TTL expires. Persistent disagreement beyond the TTL window can indicate a misconfiguration at your DNS provider.

Why are only some record types available here?

This tool focuses on the record types most relevant to checking a recent change: A, AAAA, CNAME, MX, NS, and TXT. For the full set of record types (including SOA, PTR, SRV, and CAA), use the DNS Lookup tool.

Is my query sent to a server?

No intermediate server—your browser queries Google's and Cloudflare's public DNS-over-HTTPS APIs directly. Nothing is sent to or stored by devutils.run.