This indicates an attempt to exploit a Buffer Overflow vulnerability in Bind.
An attacker can probe a target DNS server with a specific inverse query. If the DNS server is vulnerable, this may result in information disclosure. With this information, the attacker can gain access to the DNS server with the privileges of the DNS daemon, "named" (potentially root).
BIND Versions 4 and Versions 8 through 8.2 are vulnerable to the attack.
System compromise: Information leak can lead to unauthorized access by an attacker.
Update to BIND versions greater than 8.2.