This simple Powershell script will carry out a quick check against each IP in a 24 bit subnet and return a value of true or false dependent on whether or not it receives a reply.  It’s similar to using an IP scanner or a ping script.

[cc lang="powershell"]$subnet = "10.20.6."
1..254 | Foreach-Object {write-host "$Subnet$_…" (Test-Connection -ComputerName "$Subnet$_" -Quiet -Count 1 ) }[/cc]

It’s simple and does the job as it is however you could obviously make it more fancy by exporting to csv or an array or emailing the output etc etc.