The traffic requirements of various platforms influence how network devices
are configured. Five situations where traffic requirements would affect router
setup are shown in Figure
.
To check
the local host configuration on a Windows NT/2000/XP system, open a DOS command
window on the host and enter the ipconfig /all command.
The
resulting output displays the TCP/IP address configuration, default gateway,
DHCP server, and DNS server addresses. If any IP addresses are incorrect or if
no IP address is displayed, determine the correct IP address and edit it or
enter it for the local host.
The Windows NT/2000/XP platform will log
most incorrect IP address or subnet mask errors in the Event Viewer. Examine
the Event Viewer system log and look for any entry with TCP/IP or DHCP as the
source.
Read the
appropriate entries by double-clicking them.
Because DHCP
configures TCP/IP remotely, DHCP errors cannot be corrected from the local
computer.
Also, check the configurations on the NT/2000/XP server. If a
connection using an IP address is possible but the connection cannot be made
using Microsoft networking (for example, Network Neighborhood), try to isolate
a problem with the Windows NT/2000/XP server configuration. Problem areas with
Microsoft networking relate to NetBIOS support and associated mechanisms used
to resolve non-IP entities with IP addresses. Non-IP problems can be checked
using the nbtstat command.

As a last
resort, try rebooting the Windows system. Although this practice is not
encouraged, it frequently repairs the problem.
Figure
shows some
general commands used for isolating application layer problems. While many of
these commands display lower layer information, the commands are still useful
because they highlight problems in the application layer.
Figure
shows the output
of the ifconfig command.