CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [421]
Isolating the Symptom
With so many bits and pieces to a PC, you must take the time to try to isolate the symptom to ensure your fix is going to the software or hardware that really needs it. In hardware, that usually means removing suspect parts until only one possible part remains. In software, that usually means removing background programs, booting into Safe mode, or trying to create a situation where only the suspected program is running.
Isolation takes on a whole new meaning with networks. One of the greatest tools in networking is isolation—does this problem happen on other systems, on other workgroups, on other PCs running DHCP? Whenever a problem takes place in networking, isolation is the key to determining the problem.
Separating Hardware from Software
Many problems that occur on a PC are difficult to isolate given that it is difficult to determine whether the problem lies in the software or the hardware. If you find yourself in this situation, you can take a few steps to help you zero in on which side of the PC to suspect.
Known Good Hardware
The absolute best way to know whether a problem is hardware or software related is to replace the suspected piece of hardware with a known good part. If you can’t tell whether a Windows page fault comes from bad RAM or a software incompatibility, quickly replacing the RAM with known good RAM should help you determine whether the RAM or the software is to blame.
Cable and Loopback Test
A bad NIC can also generate a “can’t see the network” problem. Use whatever utility was provided with your OS to verify that the NIC works. If you have a NIC with diagnostic software, run it—this software will check the NIC’s circuitry. The NIC’s female connector is a common failure point, so NICs that come with diagnostic software often include a special test called a loopback test. A loopback test sends data out of the NIC and checks to see if it comes back. Some NICs perform only an internal loopback that tests the circuitry that sends and receives, but not the actual connecting pins. A true external loopback requires a loopback plug inserted into the NIC’s port (Figure 23-45). If a NIC is bad, replace it—preferably with an identical NIC so you don’t have to reinstall drivers.
Figure 23-45 Loopback plug
The network cable is a common source of network troubles. You can use a cable tester if you suspect a cable problem. With the right equipment, diagnosing a bad cabling run is easy. Anyone with a network should own a midrange cable tester such as the Fluke Microscanner. With a little practice, you can easily determine not only whether a cable is disconnected, but also where the disconnection takes place. Sometimes patience is required, especially if the cable runs aren’t labeled, but you will find the problem.
Uninstall/Reinstall
If you can do so easily, try uninstalling the suspected software and reinstalling. Many hardware/software problems magically disappear with a simple uninstall/reinstall.
Patching/Upgrading
Many hardware or software problems take place due to incompatibilities between the two suspect sides. Try upgrading drivers. Download patches or upgrades to software, especially if the hardware and the software are more than two years apart in age.
Virus Check
Last (maybe I should have put this first), always check for viruses. Today’s viruses manifest so many different symptoms that failure to check for them is a study in time wasting. I recently got a new hard drive that started to make a nasty clicking noise—a sure sign of a failing hard drive. However, I ran an extensive virus check and guess what—it was a virus! Who would have thought? I checked with the hard drive maker’s Web site, and my fears were confirmed. It just goes to show you—even the best of techs can be caught by the simplest problems.
Research