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How to Test a Network Adapter
Last updates: 7/26/01
Q. How do I test an Ethernet network interface
card (NIC)?
A. Most NICs or network adapters come with
one or more floppy disks containing drivers, etc. for various operating systems. These
floppies also usually include a diagnostic program to test the NIC. Many
of these programs are DOS-Based and must be run by booting the computer to
DOS or from a DOS window in Windows. Unless you have a loopback plug
installed, the loopback test will probably fail. A loopback plug directs
signals from the NIC's transmitter back to it's receiver. An indicator
that a NIC and cabling is functioning is to check the LINK (sometimes labeled
LNK, etc.) and Activity (ACT, etc.) LEDs, if there are any, on the NIC and
on the device at the other end of the cable. The LINK should be solid
with no flickering and the ACTIVITY should be blinking, which indicates,
of course, network activity. This indication is not as thorough a test
as the diagnostics program and it is not foolproof (see Why
would the Link (or LNK) LEDs be on solid, if there is a faulty cable connecting
two Ethernet devices?). The diagnostics program and LED observations
may not conclusively show that the NIC is fully functional in Windows. Look
for exclamation marks beside the NIC driver in the Windows 9x/Me Device Manager
(click Start, Settings, Control Panel, System, Device
Manger...), which indicate a resource conflict and run the Windows Resource
Conflict Troubleshooter if you find any. Look for multiple instances
of the NIC driver in the network configuration (click Start, Settings, Control
Panel, Network and remove all of them, if you find any, restart
Windows and reinstall the driver, etc. Run hwinfo (click Start, Run,
and enter hwinfo /ui). To help narrow-down problems, click View in
the main menu and select Devices with Problems. Once these steps
are completed and the NIC passes, try copying about 100 MBytes of files to
another computer on the network. Net diag and ping are useful tools
for further testing a NIC and a network. For more info, open a DOS
windows and type:
C:\>ping /?
and
C:\>net /?
Ping requires that the TCP/IP protocol be installed, and
IP addresses be assigned at both ends of the network segment to be tested.
net diag is a useful low-level network test.
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