Modern AV equipment — control processors, cameras, DSPs, streaming encoders — increasingly communicates over standard IP networks rather than dedicated AV cabling. Every device on that network needs an IP address (commonly IPv4, four numbers like 192.168.1.50) and a subnet mask that defines which addresses count as "local" versus reachable only through a router.
A VLAN (Virtual Local Area Network) logically separates traffic on the same physical switch into isolated broadcast domains — for example, keeping AV/control traffic on its own VLAN, separate from general courthouse office traffic, reduces congestion and improves security, since a compromised AV device can't freely reach the rest of the network. This is precisely the skill named in the Newark posting's required qualifications.
Switches connect devices within a network. A managed switch supports VLANs, QoS (prioritizing time-sensitive AV/video traffic over less urgent traffic), and port-level configuration — unlike a simple unmanaged switch. Many AV devices also draw power directly from the network cable via PoE (Power over Ethernet), simplifying installs by eliminating a separate power run to, say, a ceiling-mounted camera or wireless access point.
Signal-management systems handle the routing and processing side once signals are digitized: a matrix switcher routes any of several video/audio sources to any of several displays or outputs on demand; a DSP (Digital Signal Processor) mixes, equalizes, and routes audio between multiple microphones and speakers in real time; HDBaseT extenders send HDMI-equivalent video, audio, Ethernet, and control signals over a single Cat cable for long in-building runs — exactly the kind of infrastructure a courtroom AV upgrade project depends on.