The dnsmasq minimum is 2 minutes, so setting to 29 seconds doesn't
work. Setting it to 2 minutes better reflects reality.
Also using the minutes identifier (m) ensures that dnsmasq doesn't
attempt to parse the timeout as a prefix length if a IPv6 range is
provided.
Change-Id: I9e8585a7e4e5b6a21b05f3c5578c869a2c357b02