I'm probably the only person in the world who has used
a "network analyzer" in both senses:
In the modern digital networking sense, I've used Ethereal (now Wireshark) to look at IP packet contents. It shows bytes in a packet, parsed according to the various networking layers. EG a UDP packet might contain a command, and itself is wrapped in an IP header.
In the older analog sense, I've used an IC, the AD5933 which can analyze a LRC (inductor resistor capacitor) network. It sends a range of frequencies into a device and listens to the amplitude and phase of the output. Used to take a 100 lb box the size of a microwave oven; now its a chip.
This is what you get for being an eclectic engineer.
