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I recently updated a domain mapping for my domain but the TTL was several days and I'd like my local recursive resolver (a remote machine, not localhost) to update its cache.

How can I send a message to the recursive resolver to tell it that its current entry is invalid and it should talk to the authoritative nameserver?

I am running Linux locally so would prefer a command line tool that runs on Linux.

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  • ...and maybe you could send him even the answer, with the ip of the source, because of compatibility reasons. :-)
    – peterh
    Dec 27, 2014 at 4:05
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    Do you have control over that recursive resolver? Is it your ISP's?
    – Wesley
    Dec 27, 2014 at 4:09
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    Even if you were able to flush the DNS servers you are interested in, the old entries would still be cached on who knows how many other servers out there. Dec 27, 2014 at 4:25
  • It is my router. I tried resetting it but it stayed on.
    – merlin2011
    Dec 27, 2014 at 4:26
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    This question is off topic because it prominently involved software or hardware that is not professional grade and may itself be causing the problem, or actively hindering a professional, repeatable, and consistent solution.
    – Wesley
    Dec 27, 2014 at 4:58

1 Answer 1

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I recently updated a domain mapping for my domain but the TTL was several days

That'll teach you to have a long TTL for no good reason! =) 3600 seconds is the most that's reasonable in the vast majority of situations. I personally prefer 5 minutes even for domains that get hundreds of requests per second or more. Actually, especially if the record is pulled hundreds of times per second or more.

How can I send a message to the recursive resolver to tell it that its current entry is invalid and it should talk to the authoritative nameserver?

If you don't control the name server, you can't. If you do, then you'll need to search the documentation for the DNS server software to find out how to purge a specific record. Otherwise you're going to have to figure out . who to contact that controls the server. If it's an ISP, then just headbutt a claymore. Your demise will be less painful and messy.

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  • You can have a long TTL time, just make sure to reduce the TTL before any time whenever you expect the possibility of having to make changes to the DNS entries.
    – Lie Ryan
    Dec 27, 2014 at 13:07
  • @LieRyan You can, you just shouldn't. =)
    – Wesley
    Dec 27, 2014 at 19:00
  • I don't think a blanket makes any sense. A low TTL means more DNS misses, which means higher response time since the name lookup has to actually go through to the origin name server. For some types of server, the increased latency might not be sensible.
    – Lie Ryan
    Dec 27, 2014 at 19:23

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