言語

DNS Checker

Free, no signup. Ask three public resolvers the same DNS question. When their answers differ, you can see the propagation evidence instead of guessing.

Built by Patrick Stox

For PTR, enter either a reverse DNS name or an IPv4 address. Each resolver is queried independently.

Checks run from our server; we fetch the URL you enter and don't keep the results. Queries use Cloudflare, Google, and Quad9 DNS-over-HTTPS. Results are cached briefly (about one minute) so this is not an instant authoritative DNS check. Anonymous run-level outcome counters may be used for aggregate research; URLs, domains, IPs, and identifiers are never included, and no statistic is released below 100 runs.

Feedback
Report a bug

Found something broken in Dns Checker? Let us know what happened — this goes straight to a private triage queue, not a public list.

What will be sent 
 No tool inputs, uploads, pasted source, complete results, query parameters, or URL fragments are attached automatically. You can edit or remove the selected passage above. Browser and anti-abuse metadata is processed for spam prevention. 
  
 
  
 
 
  
 
 
  
 
 
Sample report
Illustrative example — fixed resolver answers
  • Cloudflare: A 192.0.2.10 (TTL 300s)
  • Google: A 192.0.2.10 (TTL 240s)
  • Quad9: A 192.0.2.20 (TTL 300s)
Signal to review: resolver answers differ. This can be propagation, split-horizon behavior, or a resolver issue; it is not automatically a bad zone.
 
 
How to use it
  1. Enter a domain or DNS name and select the record type.
  2. Choose Look up DNS to query Cloudflare, Google, and Quad9 independently.
  3. Compare answer values and TTLs, then review mismatch or resolver-error flags.
  4. Use the copyable zone-file reference for notes only; edit real records at the authoritative DNS provider.
 
 
       
     
     
What the results mean
Matching values across three recursive resolvers are consistency evidence. Different TTLs alone are normal as caches age. A value mismatch means the resolver views differ. A DNS status or network failure belongs only to that resolver and is not converted into a clean answer.
How it works
The browser sends three parallel DNS-over-HTTPS requests through the bounded endpoint. The response preserves each resolver’s status, typed answers, TTLs, authority context, and errors. Deterministic comparison rules flag differing values or unavailable resolvers, explain the selected record and response status in plain language, identify a small curated set of provider-controlled hostnames only when they appear in returned records, and convert observed answers into zone-style text.
Features
  • Eleven common record types including PTR and SRV.
  • Side-by-side Cloudflare, Google, and Quad9 results.
  • Plain-language record and DNS status explanations.
  • Evidence-led delivery and email-service hints from returned hostnames.
  • TTL, resolver status, and propagation flags.
  • Copyable observed-answer reference.
Limitations
These are cached recursive views, not direct authoritative queries, and results are briefly cached by this service. Provider hints cover only a small curated hostname set and do not prove an account is active or reveal an origin. The tool does not trace delegation, edit records, validate DNSSEC chains, test every geographic resolver, or prove the cause of a mismatch.
 
Frequently asked questions
Why do the three resolvers disagree?
Different recursive resolvers can retain old answers until their TTL expires. A mismatch can indicate propagation, split-horizon DNS, or a resolver failure; it is not by itself proof of a misconfiguration.
Does the zone-file export change DNS?
No. It is a copyable representation of observed answers, not an authoritative export and never a write to your DNS provider.
Which DNS record types can I check?
The checker supports A, AAAA, CNAME, MX, TXT, NS, SOA, CAA, SRV, and PTR. PTR accepts an IPv4 address or a reverse-DNS name.
Are these authoritative DNS answers?
No. Cloudflare, Google, and Quad9 are recursive resolvers. Their cached view is useful for propagation checks, but the domain’s authoritative nameservers are the source of record truth.
Next stepHosting Checker — look up the exact spec and expected values.

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Feature requests for Dns Checker
 

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ツールについて
CloudflareとGoogleからA、AAAA、CNAME、MX、TXT、NS、SOA、CAA、SRV、PTRの回答を比較し、DNS伝播の違いを見つけます。
機能
  • 主要DNSレコード種別の比較
  • CloudflareとGoogleの回答
  • 伝播差分と不一致の表示
  • 観測した回答のエクスポート
仕組み
対象ドメインとレコード種別を確認し、複数の公開リゾルバーから回答を取得して正規化します。値、TTL、エラー、差分を出典ごとに分けて表示します。
制限事項
  • 結果は選択したリゾルバーの実行時回答であり、世界中の伝播、キャッシュ、ゾーン設定、メール配信を保証しません。
  • DNSSEC、地域差、タイムアウト、プロバイダー固有の挙動は観測範囲外になる場合があります。
よくある質問
これはDNSの権威サーバーを確認しますか？
公開リゾルバーから見える回答を比較します。権威サーバーの設定やすべての地域の伝播を保証しません。
回答が異なる場合は何を意味しますか？
キャッシュ、伝播、リゾルバー、設定の差を示す可能性があります。ゾーンと複数地域の回答を別途確認してください。
メール配信を保証しますか？
いいえ。MXなどの回答を表示しますが、メール配信、認証、受信側ポリシーは保証しません。