This document provides an overview of fundamentals of enterprise TCP/IP networking. It discusses networking models like TCP/IP, common networking devices, IP addressing concepts including IPv4 and IPv6, and how IP addresses are divided into classes. It also covers IP subnetting which allows subdivision of IP address space into smaller subnetworks. Finally, it presents the basic model of an enterprise network and concludes with benefits of subnetting like reduced IP usage, controlled growth, and increased security.