In larger organizations, network administration and system administration are two separate jobs and tasks. There is some coordination effort that is required when provisioning a new system. Keeping and maintaining servers up and running is a separate task from keeping the routers and switches configured.
Larger organizations have teams or people assigned to administering and maintaining servers, networks, and client workstations. That tends to be the three main areas of administration.
In smaller organizations, there is usually a small team of IT specialists that are responsible for network, server, and client administration. These teams usually manage around 300 or so employees in one or more offices. As the needs and demands of the company grow, the need for the IT organization to clearly delineate which people are responsible for individual tasks.
To understand where your company falls, I would recommend taking a small inventory of the number of network devices, firewalls, routers, switches, workstations, and servers. That should provide you with a basic understanding of the network footprint and assign people to managing and maintaining those components.
This was first published in October 2008