This happens when name services are not set up correctly.
Click the Windows 95 Start button, click Programs, click PC-NFSpro, then click Configuration.
Click TCP/IP and make sure all settings are entered correctly.
If NIS is enabled, click Configure NIS and make sure the NIS domain and server names are correct.
If DNS is enabled, click Configure DNS and make sure the DNS domain and server names are correct.
Click edit hosts and add the name and IP address of the machine you are trying to ping(1M), along with the authentication server.
If you make any changes, click OK, then click Save and Exit on the Configuration dialog box. Shut down and restart Windows 95.