Simple DNS Plus 4.1, 5.0, and possibly other versions before 5.1.101 allows remote attackers to cause a denial of service via multiple DNS reply packets.
securityreason.com/securityalert/4011
www.blackhat.org.il/index.php/simple-dns-plus-5041-remote-denial-of-service-exploit/
www.securityfocus.com/archive/1/494304/100/0/threaded
www.securityfocus.com/bid/30207
www.simpledns.com/kb.aspx?kbid=1246
exchange.xforce.ibmcloud.com/vulnerabilities/43767
www.exploit-db.com/exploits/6059