DNS Propagation Checker

Ever wanted to check the result of a DNS lookup from various DNS servers, perhaps to see how far a recent DNS change has propagated – which servers are giving the new answer, and which still have the old answer cached?

I recently wrote a little Perl script to do just that. My DNS Propagation Checker will query a set of 10 servers at random and show you the results. (Be warned, it may be a little slow at times, because (a) it has to wait for the DNS servers (I might re-write it one day to do the requests concurrently) and (b) my poor little virtual server is a little slow and overloaded right now.

It’s Open Source software available under the GPL licence, but I haven’t tidied the code up and released it yet.  If you would like a copy let me know – if there’s any interest, I’ll release it.

Do let me know if you find this tool useful :)

9 thoughts on “DNS Propagation Checker”

  1. Awesome. Wish I had known of it earlier. I’d be interested in the code or at minimum knowing what the 60 DNS servers are for possible customization.

  2. @Don:

    Thanks – glad it was useful.

    No problems if you want the code – I’m planning to release it on my site soon, but would like to polish it up a little first. In the meantime I can send you the code as it is now – if you want it, drop me a mail to davidp@preshweb.co.uk.

    It’s under a GPL licence.

  3. Great tool, I’ve recently created a tool that does a similar thing but extends on your idea. It allows you to select from a range of different record types, and is displayed in a nice Google maps overlay so you can instantly see how DNS is propagating around the world.

    Anyhow, you can check it out at http://www.whatsmydns.net

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