A lot of people think arp wil do it but the arp table will only show devices you have communicated with.
Using nmap is a quick and simple way to scan a range to find a machine you may not know the IP for:
eg:
nmap -sP 10.1.5.0/24
Just change the above to your subnet
nmap, locate, servers, nmapa, arp, wil, devices, communicated, scan, ip, eg, sp, subnet,