There is more to a network than the switches, routers, controllers and servers. Networks will consist of various bits of software. Each piece of software will control a portion of the network.
Server Software
Most enterprise networks will have a server handling sever duties. The single server can act as AD, DNS, DHCP, Radius, and more. All of these work together to help get up on the network and authenticated. You will get an IP from the DHCP server. You will have your credentials located in AD. The radius will can check AD to see if your credentials are correct. If all goes to plan you will be authenticated.
DHCP
DHCP server is software dedicated to handle the IP addressing for the network. It can have several different scopes. A scope is the allotted IP addresses for that network. The DHCP server can be its own box or it can be shared in a virtual environment with other software. In some cases the DHCP duties will come from a wireless controller or router.
RADIUS
A radius server is software used for external AAA (Association, Authentication, and Accounting). It provides a more secure method of authentication with many other variables. It is also usually the backend authentication source for most enterprise networks. The radius duties can be hosted in its own machine or based in a VM. Now there is an option for cloud based radius services.
NMS (Network Management Software)
Network Management Software is dedicated to managing the parameters of your network. NMS makes the administration of your network much simpler due to a single application being able to handle everything from network configuration to finding lost devices. Like the radius server NMS can be cloud based as well as traditional VM or on a standalone machine.
WLAN Tools
There are many tools available to assist you and your network troubleshooting abilities. There are many open source Wi-Fi scanners to give you a quick look at the environment you in. Spectrum analyzers are similar to the Wi-Fi scanners in the fact that the show you what’s in the air around you. The spectrum analyzers are very accurate and require the use of a recording device to get the exact measures of RF energy. Another great piece of software is Sniffers. These sniffers capture packets transmitted and allow the user to diagnose problems in the network.
