The remote host is missing an update to nsd, nsd3 announced via advisory DSA 1803-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201803-1

Ilja van Sprundel discovered that a buffer overflow in NSD, an authoritative name service daemon, allowed to crash the server by sending a crafted packet, creating a denial of service. For the old stable distribution (etch), this problem has been fixed in version 2.3.6-1+etch1 of the nsd package. For the stable distribution (lenny), this problem has been fixed in version 2.3.7-1.1+lenny1 of the nsd package and version 3.0.7-3.lenny2 of the nsd3 package. For the unstable distribution (sid), this problem has been fixed in version 2.3.7-3 for nsd nsd3 will be fixed soon. We recommend that you upgrade your nsd or nsd3 package.