This paper presents a novel dynamically reconfigurable active L1 cache model for hybrid prototyping, called DRAC. The hybrid prototyping technique simulates a multicore embedded system using an emulation kernel on top of a single physical instance of a core. We extend hybrid prototyping by supporting memory hierarchy modeling with DRAC. The presented cache model is a standalone cycle accurate model that is further customized for multicore emulation. DRAC run-time configurability enables the embedded system designer to simulate and explore different multicore design options without the need for full FPGA prototyping. Our experimental results show 2.78% average error and 5.06% worst case error when DRAC is used as a standalone cache model in a single core design. We also observed 100% relative accuracy and less than 13% absolute worst case error in timing estimation when DRAC is used for hybrid prototyping of multicore designs.