Flush DNS cache in Ubuntu

Question

Which command can be used to flush DNS cache in Ubuntu?

Answer 1

By default in Ubuntu is no caching DNS query.

If you use remote DNS server, then you have no chance to update their cache.

If you install local server. BIND:

rndc flush

nscd:

service nscd reload

dnsmasq:

/etc/init.d/dnsmasq restart

Answer 2

In my ubuntu 11.04 , I ran this:/etc/init.d/dns-clean to clean dns it's content is as follow:

#! /bin/sh

# $Id: dns-clean,v 1.1.1.1 2004/05/07 03:12:59 john Exp $

# dns-clean by John Hasler 1999-2003
# Any possessor of a copy of this program may treat it as if it
# were in the public domain.  I waive all rights.

# This script should be run at bootup to clean up any mess left by 0dns-up.
# It should be run before ppp is started.
# It should never be run while ppp is up.

### BEGIN INIT INFO
# Provides:          dns-clean
# Required-Start:    $local_fs $remote_fs gdm
# Required-Stop:     $local_fs
# Default-Start:     1 2 3 4 5
# Default-Stop:
# Short-Description: Cleans up any mess left by 0dns-up
# Description: 0dns-up often leaves behind some cruft. This Script is meant
#              to clean up any such mess.
### END INIT INFO

PATH=/sbin:/bin:/usr/sbin:/usr/bin

test -f /usr/sbin/pppconfig || exit 0
# We might have a tmpfs /var/run.
mkdir /var/run/pppconfig >/dev/null 2>&1 || true
test -f /etc/ppp/ip-down.d/0dns-down || exit 0

. /lib/lsb/init-functions
. /etc/default/rcS

case "$1" in
  start)
    [ "$VERBOSE" != no ] && log_begin_msg "Restoring resolver state..."
    /etc/ppp/ip-down.d/0dns-down "0dns-clean"
    [ "$VERBOSE" != no ] && log_end_msg $?
    ;;
  stop|restart|force-reload)
    ;;
  *)
        ;;
esac

exit 0