Comment 20 for bug 1176046

> But perhaps it would be simpler to provide users a way to disable this functionality manually? Is there any kind of runtime configuration available?

At runtime, it doesn't seem to have a way, for instance, I already tried the following without success: do-forward-updates false;

# man dhclient.conf
       If you want to do DNS updates in the DHCP client script (see dhclient-script(8)) rather than having the DHCP client do the update directly (for example, if you want to use SIG(0) authentication, which is not supported directly by the DHCP client, you can
       instruct the client not to do the update using the do-forward-updates statement. Flag should be true if you want the DHCP client to do the update, and false if you don't want the DHCP client to do the update. By default, the DHCP client will do the DNS
       update.

To disable the functionality at the moment for Trusty, manipulation in the source package is required.

Undefine NSUPDATE in includes/site.h :

-#define NSUPDATE
+/* #define NSUPDATE */

and disabled failover and tracing in debian/rules :

./configure \
                --prefix=/usr \
                --sysconfdir=/etc/dhcp \
+ --disable-tracing \
+ --disable-failover \

Eric