DNS Forwarder - empty answers

  • Hi!
    I have a question regarding a peculiar problem with the DNS Forwarder.
    When I do the first non cached DNS-question I get an empty response. The second gives correct data.
    I then ticked the "Query DNS servers sequentially" in settings.
    This seems to solve the problem for now, but I am curios about what might cause this problem.

    // Martin

  • LAYER 8 Global Moderator

    So you were doing parallel before? In that mode if you look up www.domain.tld then that query is sent to all of your ns you have listed at same time, first one to answer wins.  If the 1st one to answer is sending back junk you get junk!

    I would make sure all the ns you have listed actually answer you and don't send back nx, etc.

  • Well, the parallel were by default, we have been upgrading since a couple of years.
    The office just moved last Thursday, so it might have something to do with our new ISP.
    Will investigate later on.

  • @Assar:

    The office just moved last Thursday, so it might have something to do with our new ISP.

    If you're still using the DNS servers your old ISP provided, then yes, I think the office move just might have something to do with it. Either use public DNS servers or find out the IPs of the nameservers your new ISP provides.

  • LAYER 8 Global Moderator

    yeah if you change isp's they quite often prevent anyone not on their network from using their dns server.  But normally you just won't connect to them.

    I would query each server you have listed to see what they send back for something your looking for.

  • The DNS servers were correctly updated, and each server is answering correct when asked.
    Something went wrong when asked in parallel.

  • LAYER 8 Global Moderator

    I find that unlikely.. Used that method for quite some time until they enabled unbound (resolver) without any issues.  Why don't you put it back to par mode and sniff and see..

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