In the world of networking education, Cisco Packet Tracer is a cornerstone tool, allowing students and professionals to design, configure, and troubleshoot networks without physical hardware. At the heart of every simulation lies a specific file type: the .pkt file . What is a .pkt file? A .pkt file is the native file format used by Cisco Packet Tracer. It serves as a project file that contains the complete state of a virtual network. When you save your work in Packet Tracer—whether it’s a single router, a complex mesh of 20 switches, or a fully configured home network—it is serialized and stored as a .pkt file.