In the past few months an exploit of DNS servers-causing a possibly devistating results. This issue has been addressed in depth by Leo Laporte and Steve Gibson on episode’s 155 and 157 of Security Now! both before and after it was actually revealed to the public. CNET | New.com published an overview of this issue… (link to it here).
It is important to add that since the patch to this critical issue has been employed, it is still possible to exploit this, however it does take (as stated on doxpara.com) “What was once possible via 32,769 packets, is still possible via between 134,217,728 and 4,294,967,296 packets.” Meaning that this evolved issue is still possible-and has been proved to take a weekend via an internal gigabit network local to a server, however this does close opportunity from abroad, but still leaves the scenario of an office computer hit with a trojan being able to poison a DNS server locally accessible.
Until this problem is solved completely you can test your DNS servers at doxpara.com , just use the “Check My DNS”… it will give you feedback based on your server, it doesn’t matter too much other feedback other than the “excellent”, “poor”, etc…
This issue will cause upcoming news, if your DNS server is at risk you can re-route your DNS requests to OpenDNS(.com)… for instructions about using OpenDNS goto OpenDNS.com. Check for upcoming news updates, and for future reference, Security Now! by Leo and Steve is a great resource to understand technology so that you can understand how it can be exploited.