3Com PalmPilot Handbook page 59

Adding a DNS Number:
If your ISP or dial-in server requires a DNS number and you have
not entered that information in the Network Preferences screen, it
will only appear that you have successfully logged on to your
network. When you try to use an application or look up
information, the connection will fail. If this occurs, try adding a
DNS number. Ask your ISP or your System Administrator for the
correct Primary and Secondary DNS IP numbers.
Chapter 3: Reference page
55