The remote host is missing an update to pdns announced via advisory DSA 2385-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202385-1

Ray Morris discovered that the PowerDNS authoritative sever responds to response packets. An attacker who can spoof the source address of IP packets can cause an endless packet loop between a PowerDNS authoritative server and another DNS server, leading to a denial of service. For the oldstable distribution (lenny), this problem has been fixed in version 2.9.21.2-1+lenny1. For the stable distribution (squeeze), this problem has been fixed in version 2.9.22-8+squeeze1. For the testing distribution (wheezy) and the unstable distribution (sid), this problem will be fixed soon. We recommend that you upgrade your pdns packages.