The first step is to enter the IP address provided by your network adminstrator.
Slackware will fill in a default value for the netmask, but check with your network administrator to get the correct value here.
If you wish to communicate with other networks besides just your own, you will need to know the address of your default gateway (router).
You now have the option to either use a DNS name server or not. If you will be using the Internet this is almost a requirement. If you will never connect to the Internet, you can answer No here.
Again, check with your network administrator to get the correct value to enter here.
Finally you are given the chance to review and correct the settings before proceeding.