How do I enable DNS caching in the NetworkManager-controlled dnsmasq?

Question

Ubuntu Desktop 12.04 uses dnsmasq to perform DNS lookups, but it is not configured to cache these results. (I have checked this by using dig to resolve names and I do not see a large improvement in the response time after the first lookup.) How do I configure the NetworkManager-controlled dnsmasq to cache the results of DNS lookups?

Answer 1

In Ubuntu 12.10 you can enable the cache of the NetworkManager-controlled dnsmasq instance by putting the line

cache-size=1000

(with your preferred number of names instead of 1000) in a new file in /etc/NetworkManager/dnsmasq.d/. To activate this change you must then do

sudo stop network-manager
sudo killall dnsmasq
sudo start network-manager

or reboot.

Answer 2

in 12.04 dnsmasq is started by NetworkManager with hard-coded (i.e. not configurable) parameter --cache-size=0.

manpages for dnsmasq says setting cache-size to zero disables caching. If you want to enable caching, you will probably have to disable the dnsmasq-plugin for NetworkManager to prevent NetworkManager from starting dnsmasq and start your own instance of dnsmasq with cache-size greater then zero.

here you can read how to disable dnsmasq-plugin for NetworkManager: http://askubuntu.com/a/131422/71057