Packet Tracer 5.3 supports activities authored in Packet Tracer 4.0, 4.1, 4.11, 5.0, 5.1 and 5.2.x . Please note that the last two courses of the CCNA Discovery and CCNA Exploration curricula require Packet Tracer version 4.11 at a minimum, CCNA Security requires version 5.2 at a minimum, and the beta Packet Tracer Skills Based Assessments require version 5.2.1 at a minimum. The curricula are fully compatible with Packet Tracer 5.3