220-1201 Hardware and Network Troubleshooting Study Guide for the CompTIA A+ Core Series Exam

When hardware and networks work well, it’s a beautiful thing. But we know this is not always the case, and as an IT support professional you will be depended upon to fix whatever goes wrong. Any device or network issue will fall within your domain. This is why hardware and network troubleshooting is the most emphasized area on the CompTIA A+ 1201 exam, with 28% (nearly one-third) of the questions pertaining to it. It is important to note that all the questions about hardware and network troubleshooting begin with a scenario.

Issues with Motherboards, RAM, CPUs, and Power

Many different situations can arise when various types of hardware components start failing. You must be able to troubleshoot common problems in response to a scenario.

Power-On Self-Test (POST) Beeps

A POST is a built-in diagnostic program in the Basic Input/Output System (BIOS) or Unified Extensible Firmware Interface (UEFI). When an error in the POST occurs, the computer performs a series of beeps, called the beep code. To identify the issue, listen to the beep code and refer to the vendor documentation to match the beep code with the corresponding error. The cause of these beeps could be problems with BIOS/UEFI configuration or hardware.

Proprietary Crash Screens

Proprietary crash screens are operating system-specific error messages that occur when there is a potentially fatal error in the system. The most common proprietary crash screens are the Windows blue screen of death (BSOD) and the macOS rotating pinwheel. Common causes of these crash screens are memory issues, which may cause application crashes or error messages.

Blank Screen

A blank or black screen is indicative of no video output. Common causes of a black screen include problems with the video card, cabling, or the screen itself. Remember that many motherboards have the video card built in, so a blank screen may indicate an issue with the motherboard itself. In that case, you can attempt to connect an external video card that, once connected, in most cases, will disable the onboard video card.

No Power

A faulty power outlet or power supply is usually the issue when there is no power. When troubleshooting, begin by testing and replacing the easiest and most obvious components first before removing and replacing the power supply.

Sluggish Performance

Sluggish performance is one of the more difficult problems to troubleshoot. Common causes include low memory, low hard drive space, failing primary components, bad applications, too many applications, or malware. A good place to start when troubleshooting on a Windows OS is to view memory usage in Task Manager, which provides real-time statistics on the CPU, RAM, hard drive, and network connection.

Overheating

Problems with the fan or heat sink, dust accumulation, or something blocking the air circulation can all cause a device to overheat. Examine the device for impediments to the cooling mechanisms, such as excess dust or improper placement for optimal ventilation. Compressed air is one way to clean excess dust accumulation, but ensure that you are blowing away from the internal components of the computer rather than further into the device.

Burning Smell

A burning smell coming from a computer system is never a good thing. If you detect a burning smell, shut down the device immediately and examine it for potential culprits. Look for melted plastic and burn marks on circuit boards. Replace affected components and monitor the new component for failure. A component that fails too quickly may be an indicator of a power supply issue.

Random Shutdown

An intermittent or random shutdown is typically a result of components overheating and failing. Intermittent shutdowns can also be caused by a bad hardware installation or an improper motherboard connection.

Application Crashes

Application crashes are often an indicator of memory-related issues, such as failing memory or not enough memory available to run the application properly. Application crashes may also be a sign of other hardware malfunctions, such as a failing motherboard or an overheating central processing unit (CPU) or graphics processing unit (GPU).

Unusual Noise

Components within a device can produce various unusual noises, each indicating a different potential problem or cause. Grinding noises can only originate from moving components within the computer, such as the hard disk drives (HDDs), fans, and optical drives. This fact eliminates all non-moving components within the device. Whirring sounds tend to originate from fans, while clicking or squealing sounds often come from the HDD.

Capacitor Swelling

Capacitors store electricity on the motherboard. When a capacitor fails, it tends to swell and produce a brownish-red residue that may seep. This phenomenon is referred to as a distended capacitor or capacitor swelling. Two options for resolving this issue include replacing the motherboard or replacing the capacitor, which requires specialized training.

Inaccurate System Date/Time

Inaccurate system date/time is most likely an indication of a bad CMOS battery. The CMOS (which stands for “complementary metal-oxide-semiconductor”) battery is responsible for retaining the computer’s settings when it is powered off and is located on the motherboard. When the CMOS battery fails, the computer will be unable to retain its BIOS/UEFI settings.

Drive and Redundant Array of Inexpensive Disks (RAID) Issues

Storage devices include persistent storage, such as storage drives and RAID storage. The most common causes of storage device problems are bad adapters, a bad or failing drive, or improper connection. You must be able to troubleshoot and diagnose problems with these systems based on a given scenario.

Light-Emitting Diode (LED) Status Indicators

LED status indicators are typically visible on storage devices. A blinking light typically indicates a busy drive, while a light that does not come on at all or stays solid may be an indicator of a problem. However, you need to look at the vendor-specific specifications for indicator lights, since the indicator lights on one product may not have the same meaning as lights on another product. For instance, a RAID display can have a light that only comes on when a problem is detected in the array.

Grinding Noises

A grinding noise originating from a storage device is a significant indicator of imminent failure in a motor or spindle within the device. This grinding sound can also be heard as squealing sounds or nails on a chalkboard. It is important to back up the affected drive immediately and replace the drive.

Clicking Sounds

A rhythmic clicking or ticking sound is an indicator of a drive that is in the process of failing. Once again, back up and replace the drive immediately.

Bootable Device Not Found

Upon bootup, a storage device is first detected by the BIOS/UEFI, and then the OS. The “Bootable Device Not Found” error can be an indicator of a complete failure to boot or the OS not being found. Check connection points and cables between the motherboard and the drive if BIOS/UEFI autodetection fails. If a proper connection does not resolve the issue, it may be a bad drive. If the BIOS/UEFI is able to detect the drive but is unable to detect the OS, the issue may lie in the master boot record (MBR).

Data Loss/Corruption

The loss or corruption of data can be caused by a failing or full drive. To remedy the issue, first attempt to remove unneeded files or applications, or defragment the drive. If this does not remedy the issue, you can attempt to format the drive and reinstall the OS. If the issue persists, the drive is most likely failing.

RAID Failure

Troubleshooting a RAID failure is similar to troubleshooting a single storage drive. First, determine if the problem originates with a single drive or the system as a whole, then proceed from there. Check the indicator lights on the RAID system for insight. Remember that the problem could originate from the type of RAID that is being employed.

Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) Failure

S.M.A.R.T. is software installed on drives that monitors hard drive reliability and performance. S.M.A.R.T. metrics, while in theory useful for diagnosing and predicting drive failure, tend to be overly complicated and difficult to parse. One useful component of S.M.A.R.T. is the ability to create performance benchmarks that may prove valuable in diagnosing potential drive failures.

Extended Read/Write Times

Extended read/write times, like data loss/corruption, can be indicators of a failing or full drive. Troubleshoot this issue as you would data loss/corruption.

Input/Output Operations Per Second (IOPS) Issues

IOPS refers to how many reads and writes a storage device can perform in a second and is listed on storage devices, such as network-attached storage (NAS) and RAID systems. A steadily declining or low IOPS may be an indicator of drive failure.

Missing Drives in OS

Missing drives in the OS may be indications of a connection issue or an improperly set up storage device. Troubleshoot missing drives by checking connections, checking the BIOS/UEFI for the enabled drive, finding the drive in disk management or disk utility, making sure the drive is prepared and partitioned properly, updating drive drivers, and checking for bad sectors, which may cause the OS to show the drive as unreadable.

Missing Array

A missing RAID array can indicate a few different issues. The missing array could be a physical issue, such as a failed drive or loose connection. Another potential cause could be a problem with the RAID controller, including misconfigurations in the detection of the controller, an incompatible controller driver, or a fault in the controller itself. A missing array could also be due to data corruption or misconfigurations in the RAID array.

Audible Alarms

RAID arrays can produce audible alarms if a problem is detected. Common causes of audible alarms include drive failure, either imminent or total, power supply failures, or cache errors. An audible alarm may also be triggered during a drive rebuild due to a failing or replaced array.

Video, Projector, and Display Issues

When troubleshooting issues with video, projectors, and displays, there are some common symptoms that should be considered prior to escalation. Remember to always check the basics first. Questions in this section will all be scenario-based.

Incorrect Input Source

An incorrect data source means that the input source for the viewing device and the input source selected for the computer are not the same. Viewing devices, such as monitors and projectors, can have multiple data ports on them, including High-Definition Multimedia Interface (HDMI), DisplayPort, or Video Graphics Array (VGA).

Physical Cabling Issues

Physical cabling can cause a wide variety of issues, such as no image being produced or an image that appears and then disappears. Visually inspect cabling for imperfections and switch out cables with known working cables to diagnose or rule out cabling issues.

Burned-Out Bulb

Burned-out bulbs are specific to projectors. Projector bulbs have a limited life. Replace the bulb to solve this issue.

Fuzzy Image

Fuzzy images can be caused by different problems depending on the display device. With a projector, check the focus mechanism. With a liquid-crystal display (LCD) screen, fuzzy images can be caused by external interference, cabling issues, or resolution settings.

Display Burn-In

Burn-in is when an image or image outline is still visible on the display. This is caused when images remain on the screen too long and a shadow or ghost of the image becomes a permanent part of the display. The only solution is to replace the display.

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Dead Pixels

Dead pixels are the result of pixels that do not fire. This issue is typically related to the hardware or the monitor itself. Replacement of the display is usually necessary to correct it.

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Flashing Screen

Often, a malfunctioning screen will either flash or flicker. A flickering screen is most likely caused by a failing backlight. You will need to replace the backlight. With a flashing screen or a screen that turns on and off, the most likely cause is a bad connection cable.

Incorrect Color Display

With an LCD monitor, an incorrect color display is most likely caused by a failing controller board, which is responsible for color mapping. Another cause of an incorrect color display can be the connection cable or the pins on the display device itself.

Audio Issues

Many display devices today have built-in audio. To troubleshoot any audio issues, first check that the audio is not muted and the audio volume is up. On the computer itself, make sure that the appropriate audio output is selected.

Dim Image

Dim images can be caused by either an issue with the display device itself, generally caused by a failing backlight, or the computer being set to a low brightness setting.

Intermittent Projector Shutdown

Intermittent projector shutdowns are most commonly caused by overheating. Check to ensure proper airflow and that fans and filters are unimpeded.

Sizing Issues

Sizing issues can affect both the projector and the video displays. With a projector, the image produced may be too large or too small for the display space. This issue may be fixed by physically moving the projection device closer or farther away from the screen or by using the size adjustment on the projector. With a video display such as a monitor, images can also be either too large or too small for the screen. To remedy this issue, access the display configurations on the connected computing device.

Distorted Image

Image distortion on a display can have multiple causes. Stretching or shrinking distortion is commonly caused by a mismatch in display size and image size, causing the computing device to adjust the image to fit the display. Pixelation can also cause image distortion, primarily when an image is zoomed in too far. Another cause of distortion is a low refresh rate, which will cause waves or flickering.