The present invention provides an integrated prevention of header, state, rate and content anomalies along with network policy enforcement for domain name service (DNS). A hardware-based apparatus helps identifying DNS rate-thresholds through continuous and adaptive learning. The apparatus can determine DNS header and DNS state anomalies and drop packets containing those anomalies. DNS queries and responses are inspected for known malicious contents using a Content Inspection Engine. The apparatus integrates advantageous solutions to prevent anomalous packets and enables a policy based packet filter for DNS.