What is the procedure to troubleshoot an iBook G4 whose networking has gone deaf?

What is the procedure to troubleshoot an iBook G4 whose networking has gone deaf?

I have an iBook G4 whose wired and airport card aren't leasing a dhcp'd IP address. ifconfig shows that neither interface has an ip address. The DHCP server is known to be good and working properly. Physical network cable works fine with another laptop.