If all configured dns servers return refused in
 response to a query; dnsmasq will end up in an infinite loop
 retransmitting the dns query resulting into high CPU load.
 Problem is caused by the dns refuse retransmission logic which does
 not check for the end of a dns server list iteration in strict mode.
 Having one configured dns server returning a refused reply easily
 triggers this problem in strict order mode. This was introduced in
 9396752c

 Thanks to Hans Dedecker <dedeckeh@gmail.com> for spotting this
 and the initial patch.