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how to flush dns of Ubuntu 12.04 LTS (GNU/Linux 3.2.0-23-generic x86_64)

have tried many things form here and here also but nothing is working

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Vikas Hardia
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2 Answers2

66

According to this SU answer "How to clear DNS cache in Ubuntu?", Ubuntu by default does not provide DNS cache service. But if you have one that you installed manually, you could usually restart those services to clean the cache. Here are some examples (source):

  • Run this command to flush DNS:

    sudo /etc/init.d/dns-clean restart

  • Followup the above command with this:

    sudo /etc/init.d/networking force-reload

  • To flush nscd DNS cache:

    sudo /etc/init.d/nscd restart

  • To flush dnsmasq DNS cache:

    sudo /etc/init.d/dnsmasq restart

  • If you use BIND this should flush DNS:

    sudo /etc/init.d/named restart

    or

    sudo rndc restart

    or

    sudo rndc exec

    BIND (>= v9.3.0) supports flushing records from a particular domain and also the lan and wan views.source Examples: 

       sudo rndc flush

    sudo rndc flushname askubuntu.com
    

    sudo rndc flush lan
    

    sudo rndc flush wan
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rusty
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    This answer is spot on. As a followup, if you have not installed a DNS caching service/local DNS server, then the best course of action is probably to restart your router. Most routers have a DNS cache built-in and turned on by default that DHCP sets up. – Reid Feb 03 '14 at 17:41
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    Thank you, both, I was going to comment above on the incomplete answers... However, this one had covered it; cool! :) – Nostromov Apr 13 '17 at 23:36
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Install nscd using the following command if not yet

sudo apt-get install nscd

Flush DNS Cache in Ubuntu by restarting the nscd 

sudo /etc/init.d/nscd restart
Maythux
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  • there is no inbuild tools? – Vikas Hardia Feb 03 '14 at 11:21
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    no @jdog, it's not - but this one is - http://askubuntu.com/questions/2219/how-do-i-clear-the-dns-cache – cwd Jun 18 '14 at 21:22
  • this did not work for me (but installation and restart commands did work fine). However, when I do ssh root@serverA, it still brings me to the old server... – bzero Aug 24 '16 at 13:52