Cisco NAC allows quarantined devices to communicate over the network with (1) DNS, (2) DHCP, and (3) EAPoUDP, which allows attackers to bypass control methods by tunneling network traffic through one of these protocols.Referenceshttp://www.securityfocus.com/archive/1/446421/100/0/threadedhttp://www.osvdb.org/30977http://www.insightix.com/files/pdf/Bypassing_NAC_Solutions_Whitepaper.pdf
