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Flushing Stale DNS in Unix

In case anyone else needs this information, I’ve just figured out that

ipconfig /flushdns

that we use in the Windows world translates to

lookupd -flushcache

in Unix/Linux/Mac OS X/BSD.


  1. It does?

    I certainly don’t have any “lookupd” on any of my Linux boxes.

    As far as I know, Linux (and most other Unix variants) doesn’t cache DNS lookups at all; however, individual applications might do so. Firefox is notorious for this.

  2. Yeah and actually it’s on CentOS as well as OS X. I’ve used it quite a bit recently. Generally the times I need it come when I start hardcoding /etc/hosts to migrate blogs, etc. Happens in Firefox and Safari, so… yeah. :)

  3. So how does that differ from rndc flush?

  4. Not saying it is different. It’s just how I do it.

  5. rndc flush deals with the nameserver itself, not the workstations which use the nameserver.

    In any case, I still haven’t even been able to FIND a lookupd on CentOS. What package is it in?

    It certainly sounds like you’re doing absolutely nothing — or something quite different from Windows.

  6. Michael, you’re right. My bad. I thought I had used it on our servers but I hadn’t and it’s not on Linux (will update entry). It’s a BSD sysutil (and thus on OS X).

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