The remote host is missing an update to nsd3 announced via advisory DSA 2515-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202515-1

Marek Vavrusa and Lubos Slovak discovered that NSD, an authoritative domain name server, is not properly handling non-standard DNS packets. his can result in a NULL pointer dereference and crash the handling process. A remote attacker can abuse this flaw to perform denial of service attacks. For the stable distribution (squeeze), this problem has been fixed in version 3.2.5-1.squeeze2. For the testing distribution (wheezy), this problem will be fixed soon. For the unstable distribution (sid), this problem has been fixed in version 3.2.12-1. We recommend that you upgrade your nsd3 packages.