ARP table

What it does: shows the IP-address ↔ hardware-address (MAC) pairs your computer has recently talked to on the local network, and labels each MAC with the hardware maker (its "OUI" vendor). Every network device has a permanent MAC address baked in by its manufacturer; this is the local table that maps those to current IPs.

What you need: nothing — it reads a table your own machine already keeps. It only shows devices you've recently communicated with, not the whole network (use Discovery for that).

Safe to run: yes — read-only, it just reads a local cache.

What to expect / reading results: each row is "this IP is at this MAC, made by this vendor." An unfamiliar vendor or a MAC you don't recognize on your segment is a starting clue for a rogue or unexpected device — cross-check it with Discovery or MAC / OUI. Vendors come from the offline table bundled with the app; nothing is looked up when the screen opens. For prefixes it doesn't know, "Look up unknown vendors online" sends only the 3-byte vendor prefix of each to api.macvendors.com — outside your network, and only when you click it.