1

I have cache enabled in my dnsmasq, because it is fast.

In some situations (for example, with VPN off), dnsmasq caches wrong results. I want a quick way to clean the cache (when I connect to the VPN for example). Restarting the service works, but it is slow (takes some seconds). I have tried sending SIGHUP, which as expected reloads the configuration, but does not flush the cache.

Is there a way to flush the dnsmasq cache without restarting it?

2

If you add the following to your dnsmasq.conf this will allow you to clear the cache on a reload rather than a restart.

clear-on-reload

Then we you want to clear the cache you trigger a reload..

pkill -HUP dnsmasq

You can check the contents (dumps stats to the log) of the cache with

pkill -USR1 dnsmasq
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  • Strange, I tried it but the cache is not cleared after HUP ...
    – blueFast
    Feb 9 at 13:47
  • Does the SIGUSR1 trigger the stats dump to logs? Feb 9 at 14:28
  • Yes. HUP triggers reload, and SIGUSR1 dumps the cache, which is not empty, even after making sure that the clear-on-reload directive is enabled in the config.
    – blueFast
    Feb 9 at 20:28
  • Weird one I use SIGHUP on my custom AP's and it works.. Now last when you restart dnsmasqd are there any warning or errors when it loads the config file?. Feb 10 at 8:16
  • Not really. I even made sure of that by forcing errors to see the difference between a good config and a bad config
    – blueFast
    Feb 11 at 11:22

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