This indicates an attack attempt against a Denial of Service vulnerability in ISC BIND.
The vulnerability is caused by an error when the vulnerable software handles certain record types containing regular expressions. It allows a remote attacker to crash the vulnerable BIND server via sending malicious DNS records to the target server.
ISC BIND 9.9.0 prior to 9.9.3b1
ISC BIND 9.8.0 prior to 9.8.5b1
ISC BIND 9.7.x
Denial of Service: Remote attackers can crash vulnerable systems.
Apply the most recent upgrade or patch from the vendor.