when you ping -a x.x.x.x you may replay with nothing because that machine you have pinged is a unix host which does not use samber( SMB server on unix ) or there is no samber server on that seagment. So ping -a is a useful tools but only for a MS network, and can easy to get a COMPUTER NAME but NOT DOMAIN NAME (DNS), and if you have anyproblem you can find the it in windows help, a chapter about win2000 comand.