I have more than 250 cpu's on network. It is too hard for me to go one by one to everyone for checking and noting the specifications of cpu on my network.
How can i know all the details of cpu's which are action/on via network?
Sound like you want to inventory your hosts on a network. There are lots of 3rd party tools that can do this via installable agent. You can also write a logon script if these are all windows machines to pull netbios name and some basic machine info and write that out to a file you can use.
Depends on if they are Windows based or Linux based or a mix of both. And then are they physiclal or virtual servers?
For the Windows systems that are part of your domain you can download for free from Microsoft sysinternals tools (like psinfo.exe). They can be run from an account with domain administrator prividledges to pull OS and hardware information on all servers in your domain. http://technet.microsoft.com/en-us/sysinternals/bb545027.aspx
For Linux it would be easiest to write a shell script that pulls the information from a list of hosts.
Your virtual system manager should have a utility to allow you to gather the information. For example VMware has the vsphere cli (command line interface) that uses powershell 3.0 to export data on the servers in the system. Data available includes various combinations of information on hosts servers, guest servers, virtual NIC's and relationships between the three just for starters.