This indicates an attack attempt to exploit a Denial of Service vulnerability in ISC BIND.
The vulnerability is due to an assertion failure in buffer.c when the vulnerable application handles a malicious dns query. A remote attacker may be able to exploit this to cause a denial of service condition on the affected system.
ISC BIND 9.0.x -> 9.8.x
ISC BIND 9.9.0->9.9.9-P2
ISC BIND 9.9.3-S1->9.9.9-S3
ISC BIND 9.10.0->9.10.4-P2
ISC BIND 9.11.0a1->9.11.0rc1
Denial of Service: Remote attackers can crash vulnerable systems or services
Apply the most recent upgrade or patch from the vendor.