IP Address

We had our Barracuda firewall go down and just got a replacement up and running. Since we’ve been back up were getting overwhelmed with spam getting through, I called Barracuda’s Tech Support and they said it’s coming from an IP address which I believe is within our company. The Boss is away on Vacation and I’m fairly new so I’m asking for help on how to figure out where this IP is coming from. Is there a way on the command prompt to ping it and show me. I tried the site Whois, with no results, I tried different commands, ping -a IP address but only getting packets sent 4 received 4 lost 0, but I’m trying to get a computer name or something. Any help would be greatly appreciated.