The wiki has tons of information but the dude will search a range of addresses and ports. When an ip and port are found the dude will "connect" a probe and add that device to that map. You can assign ranges to discover and extra hops go past router boundaries. So if you specify 192.168.1.0/24 in auto discover and set hop count to 2 the next 2 neighbor networks will be scanned. Care should be used when scanning networks since you can peg cpus on older weak equipment or if you scan a BGP router the entire table will be downloaded.
Just read the wiki and search this forum, most questions have been answered.
Lebowski
Thank you, Lebowski. before I wrote here, I read the wiki and search similar topics on the forum but cannot find helpful information.