You can start service arpwatch after 2-3days you have a databse from all client
ip,mac ,computer name ,ethernet model
if any computer change any parameter you have mail
You can query your switch if it has that information:
snmptable -v2c -c public switch-address
Otherwise, there's no magic, you'll have to probe using nmap for instance, or watch all the
broadcast ping might work depending on the OS of the hosts and firewall settings as well.