Enable dnsmasq DNS query caching on Ubuntu 16.04

Tuesday, September 19th, 2017

It appears that by default, DNS query caching is disabled in dnsmasq on Ubuntu 16.04. At least it is for my Xubuntu desktop. You can check if it’s disabled for you with the dig command:

$ dig @127.0.1.1 ubuntu.com
$ dig @127.0.1.1 ubuntu.com

Yes, run it twice. Once to add the entry to the cache, the second time to verify it’s cached.

Now check the “Query time” line. If it says anything higher than about 0 to 2 msec for the query time, caching is disabled.

;; Query time: 39 msec

To enable it, create a new file /etc/NetworkManager/dnsmasq.d/cache.conf and put the following in it:

cache-size=1000

Next, restart the network manager:

systemctl restart network-manager

Now try the dig again twice and check the Query time. It should say zero or close to zero. DNS queries are now cached, which should make browsing a bit faster. In some cases a lot faster. An additional benifit is that many ISP’s modems / routers and DNS servers are horrible, which local DNS caching somewhat mitigates.