The present invention provides a method and apparatus for searching multiple strings within a packet data using deterministic finite automata. The apparatus includes means for updating memory tables stored in a layered memory architecture comprising a BRAM, an SRAM and a DRAM; a mechanism to strategically store the relevant data structure in the three memories based on the characteristics of data, size/capacity of the data structure, and frequency of access. The apparatus intelligently and efficiently places the associated data in different memories based on the observed fact that density of most rule-sets is around 10% for common data in typical network intrusion prevention systems. The methodology and layered memory architecture enable the apparatus implementing the present invention to achieve data processing line rates over 2 Gbps.