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DNS Propagation Checker

A DNS propagation checker asks about 20 public resolvers for the same record and shows which answers already match.

This check runs on our server. The address you enter is used only for this check and is not stored.
Updated

Leave this blank to compare each resolver with the answer most of them returned.

This check runs on our server. The address you enter is used only for this check and is not stored.

Each name below is the operator of a public resolver. The same operator answers from many places, so the name is not a city.

How to use the DNS Propagation Checker

  1. Enter the domain.
  2. Choose the record type.
  3. Optional: type the value you just published, such as a new IP address.
  4. Tick the robot check and press Check. The summary counts how many resolvers returned that value.

How it works

This check runs on our server. The domain is not stored.

The same query goes out over UDP to the resolvers listed in the site config, in parallel, with about three seconds for the batch. Each row is one operator and the address that was asked. A match is yes when the answer contains the value you typed. If you leave that box empty, a match is yes when the resolver agrees with the answer that most of the others returned.

Resolvers that time out, refuse, or have no record of that type count as not matching. The whole check stays inside a few seconds. Rows that did not answer in time are marked, not left spinning.

Examples

  • If 18 resolvers return 203.0.113.10 and you typed that address, the summary reads "18 of 20 resolvers return the new value."
  • With the expected box empty, the same 18 are a match against the majority, and the two that still have the old address are not.
  • A resolver that does not answer in three seconds shows "No answer within 3 seconds" and does not count as a match.

Limitations

  • Public resolvers are anycast. A resolver's name is the company that runs it, not a city, so this page has no world map.
  • Your own ISP's resolver is not in the list. It can lag behind the public ones, or the other way around.
  • One record type per check. Run it again for a second type.

Frequently asked questions

How long does propagation take?

Up to the TTL of the record you replaced. A resolver that cached the old answer keeps it until that timer ends. A few resolvers keep answers longer than the published TTL.

Why is there no map?

The addresses in the list are anycast. 1.1.1.1 is answered from many cities. Pinning that row to one country would be a guess.

Does a full match mean every user sees the new record?

It means these public resolvers do. A recursive resolver at an ISP can still hold the previous answer until its cache expires.

Often used together with the DNS Propagation Checker.

  • DNS Lookup

    One table of A, AAAA, MX, NS, TXT, SOA, and CAA records for a domain.

  • NS Lookup

    Name servers from the NS records, with TTL.