3.4.1 Hardware Failure Issues

3.4.1 Hardware Failure Issues When you are using the CompTIA Network+ troubleshooting model, it is wise to rule out physical hardware failure and Data Link layer issues before diagnosing a Network layer or application issue. Power Issues Like any computer system, networks require stable power to operate properly. Power anomalies, such as surges and spikes, can damage devices, under-voltage events (very brief power loss) can cause systems to lock up or reboot, while power failures will down everything, including the lights. Enterprise sites have systems to protect against these issues. Uninterruptible power supplies (UPSs) can keep servers, switches, and routers running for a few minutes. This provides time to either switch in a secondary power source (a generator) or shut down the system gracefully, hopefully avoiding data loss. Most power problems will have to be escalated to an electrician or the power company, depending on where the fault lies. Hardware Failure Issues If power is not the issue, consider other components that might have experienced hardware failure, including host network adapters, switch appliances, and the cabling between them. Complete hardware failure is relatively uncommon, so if you can rule out power and cabling problems, then for a network adapter, verify that the driver is working correctly. The easiest thing to do is to replace the driver (in Windows, use Device Manager to do this). For a network appliance, use status LEDs to confirm operation and check that things such as plug-in cards and modules are seated correctly. You should also consider overheating as a potential cause of hardware issues. Make sure there is good airflow around the intake and outlet vents. Check that fans and internal components are not clogged with dust and that systems are not exposed to direct sunlight.At the Data Link layer, most wired hosts connect to the network via a switch. If you suspect a device such as a switch, analyze the topology of your network. You should be able to view those users who are suffering from the problem, identify which part of the network is affected, and identify the problem bridging or switching device.When you have narrowed the problem to a device, you must determine what the nature of the problem is. It is always worth resetting the switch to see if that resolves the problem. Often, restarting network devices can clear transitory errors.