The remote Debian host is missing a security-related update.
It was discovered that the BIND DNS server does not properly handle the parsing of incoming responses, allowing some records with an incorrect class to be accepted by BIND instead of being rejected as malformed. This can trigger a REQUIRE assertion failure when those records are subsequently cached. A remote attacker can exploit this flaw to cause a denial of service against servers performing recursive queries.
Upgrade the bind9 packages. For the oldstable distribution (wheezy), this problem has been fixed in version 1:9.8.4.dfsg.P1-6+nmu2+deb7u8. For the stable distribution (jessie), this problem has been fixed in version 1:9.9.5.dfsg-9+deb8u4.