network scan for live ip script

I need a script to see at a request time the ip’s on the network - in fact i need a file on a remote server with the ip’s on the moment of the request.

Now, my 1st idea was to use ip-scan from remote server (ssh command), but i have many different subnets and that means i have to issue many commands at every minute for every subnet and it takes way to much.

Someone have an ideea, pls ?

sorry for repeating.. but nobody knows ?