As a principal network engineer, you are responsible for the daily operations of a computer system. Your responsibilities are to install, organize, and support systems for an organization. The systems you work with often aid a company in its communications, as with local area networks and wide area networks. Other duties include the installation of hardware, regular system maintenance, and optimization of network performance. You might also train individuals in the use of relevant software or hardware. In some cases, you might help with email and data storage.