DNS Propagation Checker

About DNS propagation checker

DNS Propagation Checker asks four independent public resolvers for the same record over DNS-over-HTTPS and compares what they return. If all four agree, a change has reached them. If not, you can see which resolvers still hold the old answer, which is useful after a migration or a nameserver switch.

How to use it

1. Enter the domain or subdomain in the Domain box, for example www.example.com.
2. Choose the record type from the Record type list: A, AAAA, CNAME, MX, TXT or NS.
3. Press Check propagation and wait a few seconds for all four resolvers to answer.
4. Read the Verdict for In sync or Resolvers disagree, then the Answer per resolver list.
5. If answers differ, open Conflicting answers to see which resolvers share each version.

One resolver still on the old address

A record; Google and Cloudflare return 203.0.113.10, AdGuard returns 198.51.100.7, NextDNS times out

Resolvers disagree, 2 different A answers are live. Either propagation is still in flight, or the domain uses geo-based DNS. The timed-out resolver is listed separately as unreachable, not counted as a disagreement.

When to use it

• Confirming a new A record is visible everywhere after moving to a new host.
• Watching a nameserver change spread by re-running the NS check every few minutes.
• Verifying a TXT verification token is published before you click verify in a vendor dashboard.
• Explaining to a client why their site still loads from the old server on some networks.

Questions about DNS propagation checker

Which resolvers are queried?

Four fixed public ones: Google, Cloudflare, AdGuard and NextDNS. The tool contacts them over HTTPS from our server, so the domain is sent to us first, and each has a 6 second timeout.

Is a disagreement always a propagation problem?

No. Load-balanced and geo-steered DNS legitimately answers differently, and round-robin sets can differ in order. The tool sorts values and normalizes text first, so only real differences count.

Why is a resolver marked as an error?

It failed to answer at all, through a timeout or a server error, so it can neither confirm nor deny the change. Failed resolvers are excluded from the verdict and listed separately.

How long does propagation take?

It depends on the previous record's TTL. Resolvers can keep the old answer until that time expires, so lowering the TTL a day before a planned change makes the switch much faster.

Can I check more record types?

Only the six in the list. About 10 checks per minute are allowed per visitor, since each run fans out to four resolvers.

Related tools

• DNS LookupLook up DNS records for a domain
• IPv6 support checkerCheck whether a domain's website, mail hosts, and nameservers are reachable over IPv6.
• IP LookupLook up information about an IP address
• WHOIS LookupLook up WHOIS information for a domain
• PingPing a domain or IP address
• SSL LookupLook up SSL certificate information for a domain