Open command prompt (start menu > cmd or C:/windows/system32/cmd.exe)
The following command will display the service tag of the PC you're on. bios get serialnumber
If your looking for the tag of a different PC on the same network type the below command instead. wmic /node: 10.11.12.123 /user:username /password:password bios get serialnumber
where 10.11.12.123 is the IP of the PC and user/password are admin account credentials.
To find the IP of a computer on network type the below command. nslookup pc-name
To find the MAC address of a computer on network type the below command. arp -a 10.11.12.123
where 10.11.12.123 is the IP of the PC.