The remote host is missing an update to maradns announced via advisory DSA 1445-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201445-1

Michael Krieger and Sam Trenholme discovered a programming error in MaraDNS, a simple security-aware Domain Name Service server, which might to denial of service through malformed DNS packets. For the stable distribution (etch), this problem has been fixed in version 1.2.12.04-1etch2. For the old stable distribution (sarge), this problem has been fixed in version 1.0.27-2. For the unstable distribution (sid), this problem has been fixed in version 1.2.12.08-1. We recommend that you upgrade your maradns package.