Excessive Heat

Electronic components produce heat; it’s a fact of life. While they’re designed to withstand a certain amount of the heat that’s produced, excessive heat can drastically shorten the life of components. There are two common ways to reduce heat-related problems in computers: heat sinks and cooling systems, such as case fans.

Any component with its own processor will have a heat sink. Typically these look like big, finned hunks of aluminum or another metal attached to the processor. Their job is to dissipate heat from the component so that it doesn’t become too hot. Never run a processor without a heat sink!

Case fans are designed to take hot air from inside the case and blow it out of the case. There are many different designs, from simple motors to high-tech liquid-cooled models. Put your hand up to the back of your computer at the power supply fan and you should feel warm air. If there’s nothing coming out, you either need to clean your fan out or replace your power supply. Some cases come with additional cooling fans to help dissipate heat. If your case has one, you should feel warm air coming from it as well.

We’ve mentioned dust before and now is a good time to bring it up again. Dust, dirt, grime, paint, smoke, and other airborne particles can become caked on the inside of the components. This is most common in automotive and manufacturing environments. The contaminants create a film that coats the components, causing them to overheat and/or conduct electricity on their surface. Blowing out these exposed systems with a can of compressed air from time to time can prevent damage to the components. While you’re cleaning the components, be sure to clean any cooling fans in the power supply or on the heat sink.

One way to ensure that dust and grime don’t find their way into your computer is to always leave the blanks (or slot covers) in the empty slots on the back of your box. Blanks are the pieces of metal or plastic that come with the case and cover the expansion slot openings. They are designed to keep dirt, dust, and other foreign matter from the inside of the computer. They also maintain proper airflow within the case to ensure that the computer doesn’t overheat.

Noise

Have you ever been working on a computer and heard a noise that resembles fingernails on a chalkboard? If so, you will always remember that sound, along with the impending feeling of doom as the computer stops working.

Some noises on a computer are normal. The POST beep (which we’ll talk about in a few pages) is a good sound. The whirring of a mechanical hard drive and power supply fan are familiar sounds. Some techs get so used to their “normal” system noises that if anything is slightly off pitch, they go digging for problems even if none are readily apparent.

For the most part, the components that can produce noise problems are those that move. Mechanical hard drives have motors that spin the platters. Power supply fans spin. CD and DVD drives spin the disks. If you’re hearing excessive noise, these are the likely culprits.

If you hear a whining sound and it seems to be fairly constant, it’s more than likely a fan. Either it needs to be cleaned (desperately) or replaced. Power supplies that are failing can also sound louder and quieter intermittently because a fan will run at alternating speeds.

The “fingernails on a chalkboard” squealing could be an indicator that the heads in a mechanical hard drive have crashed into the platter. This thankfully doesn’t seem to be as common today as it used to be, but it still happens. Note that this type of sound can also be caused by a power supply fan’s motor binding up. A rhythmic ticking sound is also likely to be caused by a mechanical hard drive.

Problems with the CD-ROM or DVD-ROM drive tend to be the easiest to diagnose. Those drives aren’t constantly spinning unless you put some media in them. If you put a disc in and the drive makes a terrible noise, you have a good idea what’s causing the problem.

So what do you do if you hear a terrible noise from the computer? If it’s still responsive, shut it down normally as soon as possible. If it’s not responsive, then shut off the power as quickly as you can. Examine the power supply to see if there are any obvious problems such as excessive dust, and clean it as needed. Power the system back on. If the noise was caused by the hard drive, odds are that the drive has failed and the system won’t boot normally. You may need to replace some parts.

If the noise is mildly annoying but doesn’t sound drastic, boot up the computer with the case off and listen. By getting up close and personal with the system, you can often tell where the noise is coming from and then troubleshoot or fix the appropriate part.

Odors and Smoke

Bad smells or smoke coming from your computer are never good things. While it normally gets pretty warm inside a computer case, it should never be hot enough inside there to melt plastic components, but it does happen from time to time. And power problems can sometimes cause components to get hot enough to smoke.

If you smell an odd odor or see smoke coming from a computer, shut it down immediately. Open the case and start looking for visible signs of damage. Things to look for include melted plastic components and burn marks on circuit boards. If components appear to be damaged, it’s best to replace them before returning the computer to service.

Status Light Indicators

Many hardware devices have status light indicators that can help you identify operational features or problems with a device. Obviously, when you power on a system, you expect the power light to come on. If it doesn’t, you have a problem. The same holds true for other external devices, such as wireless routers, external hard drives, and printers. In situations in which the power light doesn’t come on and the device has no power, always obey the first rule of troubleshooting: Check your connections first!

Beyond power indicators, several types of devices have additional lights that can help you troubleshoot. If you have a hub, switch, or other connectivity device, you should have an indicator for each port that lights up when there is a connection. Some devices will give you a green light for a good connection and a yellow or red light if they detect a problem. A lot of connectivity devices will also have an indicator that blinks or flashes when traffic is going through the port. Sometimes it’s the same light that indicates a connection, but at other times it’s a separate indicator. The same holds true for NICs. They usually have a connectivity light and a transmission light. If no lights are illuminated, it can indicate a lack of connection.

Many computers also have hard drive activity lights. When disk reads or writes occur, the light will blink, otherwise it will be off. A hard drive indicator that is constantly on is generally not a good sign; it could indicate that the hard drive is constantly busy or that the system is frozen, either of which is bad.

If you have a device with lights and you’re not sure what they mean, it’s best to check the manual or the manufacturer’s website to learn about them.

Alerts

An alert is a message generated by a hardware device. In some cases, the device has a display panel that will tell you what the alert is. A good example of this is an office printer. Many have an LCD display that can tell you if something is wrong. Other devices, particularly rack-mounted servers or connectivity devices, will have status lights that indicate that there’s an issue.

Other alerts will pop up on the computer screen. If the device is attached to a specific computer, the alert will generally pop up on that computer’s screen. Some devices can be configured to send an alert to a specific user account or system administrator, so the administrator will get the alert regardless of which computer they are currently logged into.

Visible Damage

The good news about visible damage is that you can usually figure out which component is damaged pretty quickly. The bad news is that it often means you need to replace parts.

Visible damage to the outside of the case or the monitor casing might not matter much as long as the device still works. But if you’re looking inside a case and see burn marks or melted components, that’s a sure sign of a problem. Replace damaged circuit boards or melted plastic components immediately. After replacing the part, it’s a good idea to monitor the new component for a while too. It could be the power supply causing the problem. If the new part fries quickly too, it’s time to replace the power supply as well.

Identifying I/O Port and Cable Problems

Input/output (I/O) ports are most often built into the motherboard and include legacy parallel and serial, USB, and FireWire ports. All of them are used to connect external peripherals to the motherboard. When a port doesn’t appear to be functioning, make sure the following conditions are met:

• The cables are snugly connected.
• The port has not been disabled in BIOS Setup.
• The port has not been disabled in Device Manager in Windows.
• No pins are broken or bent on the male end of the port or on the cable being plugged into it.

If you suspect that it’s the port, you can purchase a loopback plug to test it sfunctionality. If you suspect that the cable, rather than the port, may be the problem, swap out the cable with a known good one. If you don’t have an extra cable, you can test the existing cable with a multimeter by setting it to ohms and checking the resistance between one end of the cable and the other.

Use a pin-out diagram, if available, to determine which pin matches up to which at the other end. There is often—but not always—an inverse relationship between the ends. In other words, at one end pin 1 is at the left, and at the other end it’s at the right on the same row of pins. You see this characteristic with D-sub connectors where one end of the cable is male and the other end is female.

Distended Capacitors

Many motherboards have capacitors on them, which store electricity. They are short cylindrical tubes. Figure 12.3 shows three of them on the left side of the motherboard. Sometimes, when capacitors fail, they will bulge and brownish-red electrolyte residue may seep out of the vents in the top. These are called distended capacitors. If a capacitor fails, the motherboard will not work. You have a few options. The first and probably best option is to replace the motherboard. Whatever you do, do not touch the residue coming from a distended capacitor! The second option is to drain the energy from the failed capacitor and replace it. Only do this if you have specialized training on how to deal safely with capacitors because they can cause lethal shocks.

Identifying Cooling Issues

A PC that works for a few minutes and then locks up is probably experiencing overheating because of a heat sink or fan not functioning properly. To troubleshoot overheating, first check all fans inside the PC to ensure that they’re operating, and make sure that any heat sinks are firmly attached to their chips.

In a properly designed, properly assembled PC case, air flows in a specific path driven by the power supply fan and using the power supply’s vent holes. Make sure that you know the direction of flow and that there are limited obstructions and no dust buildup. Cases are also designed to cool by making the air flow in a certain way. Therefore, operating a PC with the cover removed can make a PC more susceptible to overheating, even though it’s “getting more air.”

Similarly, operating a PC with expansion-slot covers removed can inhibit a PC’s ability to cool itself properly because the extra holes change the airflow pattern from what was intended by its design.

Although CPUs are the most common component to overheat, occasionally other chips on the motherboard, such as the chipset or chips on other devices, particularly video cards, may also overheat. Extra heat sinks or fans may be installed to cool these chips.

Liquid cooling systems have their own set of issues. The pump that moves the liquid through the tubing and heat sinks can become obstructed or simply fail. If this happens, the liquid’s temperature will eventually equalize with that of the CPU and other components, resulting in their damage. Dust in the heat sinks has the same effect as with nonliquid cooling systems, so keep these components as clean as you would with any such components. Check regularly for signs of leaks that might be starting, and try to catch them before they result in damage to the system.

Exercise 12.1 walks you through the steps of troubleshooting a few specific hardware problems. The exercise will probably end up being a mental one for you, unless you have the exact problem that we’re describing here. As practice, you can write down the steps that you would take to solve the problem and then check to see how close you came to our steps. Clearly, there are several ways to approach a problem, so you might use a slightly different process, but the general approach should be similar. Finally, when you have found the problem, you can stop. As you go through each step, assume that it didn’t solve the issue so you need to move on to the next step.

S.M.A.R.T.

As of 2004, nearly every hard drive has been built with Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) software installed on them, which monitors hard drive reliability and theoretically can warn you in the event of an imminent failure. The idea behind S.M.A.R.T. is great. Who wouldn’t want to know when their hard drive was going to fail so they could back up the drive? In practice, though, it seems to help manufacturers locate persistent issues by identifying hard drive design flaws more than it helps end users avoid catastrophic data losses. Helping hard drive manufacturers do a better job isn’t a bad thing, but S.M.A.R.T. hasn’t enjoyed widespread commercial success with end users. This can largely be attributed to three factors:

• Windows OSs don’t come with a built-in graphical utility to parse the data.
• The 70 metrics provided by S.M.A.R.T. aren’t always easy to understand, and there has been little guidance as to which metric or metrics are most closely associated with impending drive failure.
• Manufacturers have not consistently defined the metrics among themselves; there are no industry-wide analysis applications or standards for this technology.

Let’s address the three issues in order. First, you can download one of several graphical tools from the Internet if you want to run S.M.A.R.T. diagnostics on a hard drive. Table 12.1 gives you a few options. Each one has a free option, and they all offer a variety of hard drive diagnostic capabilities.

Second, yes there are a lot of metrics that S.M.A.R.T. reports, and not all of them make sense in English. Figure 12.4 shows the output from GSmartControl. Looking at it, you can tell that three metrics appear to be problematic because they are highlighted in pink (warning) or red (failed). The question is, which metrics are most likely to predict drive failure?

In 2014, Google and cloud service provider Backblaze ran large-scale tests to determine which metrics most strongly correlated with drive failure. Their results showed five metrics, which are highlighted in Table 12.2.

Interestingly enough, metrics related to higher temperatures or the number of reboots did not correlate to drive failure. The old adage that you should leave your computer running to make the hard drive last longer wasn’t verified by the research. In addition, over half of the drives in the study failed without recording a sector error, and over 30 percent of the drives failed with no S.M.A.R.T. error whatsoever.

What does that mean for the drive shown in Figure 12.4, which has errors on ID 5? Maybe not much. The same drive passed that ID when scanned with SpeedFan (see Figure 12.5). The safe conclusion is that S.M.A.R.T. can provide useful diagnostics on a hard drive’s health, but it’s by no means a guaranteed problem finder.

As for the last issue, there being little consistency between hard drive manufacturers, that’s an annoyance but not a critical issue. All it really means is that you can’t compare data from one drive manufacturer with that of another. It’s likely that if you’re running S.M.A.R.T. data on a hard drive, you’re primarily concerned with that drive’s performance and not how it compares to other hard drives anyway. If you have a situation where you’re worried about a drive, you can benchmark its performance and track it over time, or you can just replace it.

RAID Issues

If you are using a Redundant Array of Independent Disks (RAID) system, you have additional challenges to deal with. First, you have more disks, so the chance of having a single failure increases. Second, you more than likely have one or more additional hard disk controllers, so again you introduce more parts that can fail. Third, there will likely be a software component that manages the RAID array.

Boiling it down, though, dealing with RAID issues is just like dealing with a single hard drive issue, except that you have more parts that make up the single storage unit. If your RAID array isn’t found or stops working, try to narrow down the issue. Is it one disk that’s failed, or is the whole system down, indicating a problem with a controller or the software? Along with external enclosures, which require a separate connection to the computer, most external RAID systems have status indicators and troubleshooting utilities to help you identify problems. Definitely use those to your advantage.

Finally, the problem could be dependent on the type of RAID you’re using. If you are using RAID 0 (disk striping), you actually have more points of failure than a single device, meaning that you’re at a greater risk of failure versus using just one hard drive. One drive failure will cause the entire set to fail. RAID 1 (disk mirroring) increases your fault tolerance; if one drive fails, the other has an exact replica of the data. You’ll need to replace the failed drive, but unless both drives unexpectedly fail, you shouldn’t lose any data. If you’re using RAID 5 (disk striping with parity), a single drive failure usually means that your data will be fine, provided you replace the failed drive. RAID 10 is a mirrored striped set. As long as one drive in each mirrored pair is functional (just like in RAID 1), you shouldn’t lose any data.

Low Print Quality

Problems with print quality are easy to identify. When the printed page comes out of the printer, the characters may be too light or have dots missing from them. Table 12.3 details some of the most common print quality problems, their causes, and their solutions.

Printout Jams Inside the Printer

Printer jams (aka “the printer crinkled my paper”) are very frustrating because they always seem to happen more than halfway through your 50-page print job, requiring you to take time to remove the jam before the rest of your pages can print. A paper jam happens when something prevents the paper from advancing through the printer evenly. There are generally three causes of printer jams: an obstructed paper path, stripped drive gears, and using the wrong paper.

Obstructed paper paths are often difficult to find. Usually it means disassembling the printer to find the bit of crumpled-up paper or other foreign substance that’s blocking the paper path. A common obstruction is a piece of the “perf”—the perforated sides of tractor-feed paper—that has torn off and gotten crumpled up and then lodged in the paper path. It may be necessary to remove the platen roller and feed mechanism to get at the obstruction.

Stripped drive gears cause the paper to feed improperly, causing it to crinkle and cause jams. Using the wrong paper, such as thick paper when the platen has been set for thin paper, can also cause jams. When loading new paper, always be sure that the platen is properly adjusted.

Stepper Motor Problems

Printers use stepper motors to move the print head back and forth as well as to advance the paper. The carriage motor is responsible for the back-and-forth motion while the main motor advances the paper. These motors get damaged when they are forced in any direction while the power is on. This includes moving the print head over to install a printer ribbon as well as moving the paper-feed roller to align paper. These motors are very sensitive to stray voltages. If you are rotating one of these motors by hand, you are essentially turning it into a small generator and thus damaging it.

A damaged stepper motor is easy to detect. Damage to the stepper motor will cause it to lose precision and move farther with each step. If the main motor is damaged (which is more likely to happen), lines of print will be unevenly spaced. If the print head motor goes bad, characters will be scrunched together. If a stepper motor is damaged badly enough, it won’t move at all in any direction; it may even make high-pitched squealing noises. If any of these symptoms appear, it’s time to replace one of these motors.

Stepper motors are usually expensive to replace—about half the cost of a new printer! Damage to them is easy to avoid; the biggest key is to not force them to move when the power is on.

Print Quality

The majority of inkjet printer problems are quality problems. Ninety-nine percent of these can be traced to a faulty ink cartridge. With most inkjet printers, the ink cartridge contains the print head and the ink. The major problem with this assembly can be described by “If you don’t use it, you lose it.” The ink will dry out in the small nozzles and block them if they are not used at least once a week.

An example of a quality problem is when you have thin, blank lines present in every line of text on the page. This is caused by a plugged hole in at least one of the small, pinhole ink nozzles in the print cartridge. Another common problem is faded printing. Replacing the ink cartridge generally solves these issues.

If an ink cartridge becomes damaged or develops a hole, it can put too much ink on the page and the letters will smear. Again, the solution is to replace the ink cartridge. (You should be aware, however, that a very small amount of smearing is normal if the pages are laid on top of each other immediately after printing.)

One final print quality problem that does not directly involve the ink cartridge occurs when the print quickly goes from dark to light and then prints nothing. As we already mentioned, ink cartridges dry out if not used. That’s why the manufacturers include a small suction pump inside the printer that primes the ink cartridge before each print cycle. If this priming pump is broken or malfunctioning, this problem will manifest itself and the pump will need to be replaced.

After you install a new cartridge into many inkjet printers, the print heads in that cartridge must be aligned. Print head alignment is the process by which the print head is calibrated for use. A special utility that comes with the printer software is used to do this. You run the alignment utility, and the printer prints several vertical and horizontal lines with numbers next to them. It then shows you a screen and asks you to choose the horizontal and vertical lines that are the most “in line.” Once you enter the numbers, the software understands whether the print head(s) are out of alignment, which direction, and by how much. The software then makes slight modifications to the print driver software to tell it how much to offset when printing. Occasionally, alignment must be done several times to get the images to align properly.

Color Output Problems

Sometimes, when you print a color document, the colors might not be the same colors that you expected based on what you saw on the screen. A few different issues could cause this problem. First, ink could be bleeding from adjacent areas of the picture, causing the color to be off. A leaking cartridge can cause this, as can using the wrong type of paper for your printer.

If you know that you’re using the right paper, try cleaning the print cartridges using the software utility that should have been included with the printer software. Once you do that, print a test page to confirm that the colors are correct. On most color printers, the test page will print colors in a pattern from left to right that mirrors the way the ink cartridges are installed. That brings us to our second potential problem: the ink cartridges are installed in the wrong spot. (This is for printers with multiple color ink cartridges.) That should be easy to check. Obviously, if that’s the problem, put the color cartridges where they’re supposed to be!

Third, if the ink that comes out of the cartridge doesn’t match the label on the cartridge, try the self-cleaning utility. If that doesn’t help, replace the cartridge. Finally, if one of the colors doesn’t come out at all and self-cleaning doesn’t help, just replace the cartridge.

Paper Jams

Inkjet printers have pretty simple paper paths. Therefore, paper jams due to obstructions are less likely than they are on dot-matrix printers. They are still possible, however, so an obstruction shouldn’t be overlooked as a possible cause of jamming.

Paper jams in inkjet printers are usually due to one of two things:

• A worn pickup roller
• The wrong type of paper

The pickup roller usually has one or two D-shaped rollers mounted on a rotating shaft. When the shaft rotates, one edge of the D roller rubs against the paper, pushing it into the printer. When the roller gets worn, it gets smooth and doesn’t exert enough friction against the paper to push it into the printer.

If the paper used in the printer is too smooth, it can cause the same problem. Pickup rollers use friction, and smooth paper doesn’t offer much friction. If the paper is too rough, on the other hand, it acts like sandpaper on the rollers, wearing them smooth. Here’s a rule of thumb for paper smoothness: paper slightly smoother than a new dollar bill will work fine.

Paper-Feeding Problems

You will normally see one of two paper-feeding options on an inkjet printer. The first is that the paper is stored in a paper tray on the front of the printer. The second, which is more common on smaller and cheaper models, is for the paper to be fed in vertically from the back of the printer in a paper feeder. Both types may also have manual feed or envelope feed options.

Regardless of the feed style, the printer will have a paper-feed mechanism, which picks up the paper and feeds it into the printer. Inside the paper-feed mechanism are pickup rollers, which are small rubber rollers that rub up against the paper and feed it into the printer. They press up against small rubber or cork patches known as separator pads. These help to keep the rest of the paper in the tray so that only one sheet gets picked up at a time. A pickup stepper motor turns the pickup rollers.

If your printer fails to pick up paper, it could indicate that the pickup rollers are too worn. If your printer is always picking up multiple sheets of paper, it could be a couple of things, such as problems with the separator pads or your paper being too “sticky,” damp, or rough. Some printers that use vertical paper feeders have a lever with which you can adjust the amount of tension between the pickup rollers and the separator pads. If your printer is consistently pulling multiple sheets of paper, you might want to try to increase the tension using this lever.

The final component is the paper-feed sensor. This sensor is designed to tell the printer when it’s out of paper, and it rarely fails. When it does, the printer will refuse to print because it thinks it is out of paper. Cleaning the sensor might help, but if not, you should replace the printer.

Stepper Motor Problems

Inkjet printers use stepper motors, just like dot-matrix printers. On an inkjet, the print head carriage is the component containing the print head that moves back and forth. A carriage stepper motor and an attached belt (the carriage belt) are responsible for the movement. So the print head carriage stays horizontally stable, it rests on a metal stabilizer bar. Another stepper motor is responsible for advancing the paper.

Stepper motor problems on an inkjet will look similar to the ones on a dot-matrix printer. That is, if the main motor is damaged, lines of print will be unevenly spaced, and if the print head motor goes bad, characters will be scrunched together. A lot of damage may cause the stepper motor to not move at all and possibly make high-pitched squealing noises. If any of these symptoms appear, it’s time to replace one of these motors. As with dot-matrix printers, stepper motors can be expensive. It may make more economical sense to replace the printer.

Power Problems

Inkjet printers have internal power circuits that convert the electricity from the outlet into voltages that the printer can use, typically 12V and 5V. The specific device that does this is called the transformer. If the transformer fails, the printer will not power up. If this happens, it’s time to get a new printer.

Power Problems

If you turn your laser printer on and it doesn’t respond normally, there could be a problem with the power it’s receiving. Of course, the first thing to do is to ensure that it’s plugged in!

A laser printer’s DC power supply provides three different DC voltages to printer components. This can all be checked at a power interface labeled J210, which is a 20-pin female interface. Pin 1 will be in the lower-left corner, and the pins along the bottom will all be odd numbers, increasing from left to right.

Using the multimeter, you should find the following voltages:

• Pin 1 +5v
• Pin 5 –5v
• Pin 9 +24v

If none of the voltages are reading properly, then you probably need to replace the fuse in the DC power supply. If one or more (but not all) of the voltages aren’t reading properly, then the first thing to do is to remove all optional hardware in the printer (including memory) and test again. If the readings are still bad, it’s likely you need to replace the DC power supply.

No Connectivity (IP Issues)

You can connect many laser printers directly to your network by using a network cable (such as Category 5e or 6a) or by using a wireless network adapter with the printer. In cases like these, the printer acts as its own print server (typically print server software is built into the printer), and it can speed up printing because you don’t have a separate print server translating and then sending the directions to the printer.

For printers such as these, no connectivity can be a sign of improperly configured IP settings such as the IP address. While each printer is somewhat different, you can manually configure most laser printers’ IP settings a number of ways:

• Through the printer’s LCD control panel. For example, on several HP LaserJet models, you press Menu, navigate to the Network Config menu, select TCP/IP Config, select Manual, and then enter the IP address. You would then also configure the subnet mask and default gateway.
• By using Telnet to connect to the printer’s management software from your computer.
• By using the management software that came with your printer.

You can also configure most IP printers to obtain an IP address automatically from a Dynamic Host Configuration Protocol (DHCP) server. Whenever the printer is powered up, it will contact the server to get its IP configuration information just like any other client on the network. While this may be convenient, it’s usually not a good idea to assign dynamic IP addresses to printers. Client computers will have their printer mapped to a specific IP address; if that address is changed, you will have a lot of people complaining about no connectivity. If you are using the DHCP server to manage all of your network’s IP addresses, be sure to reserve a static address for the printers.

Nothing Prints

You tell your computer to print, but nothing comes out of the printer. That problem is probably the most challenging to solve because several different things could cause it. Are you the only one affected by the problem, or are others having the same issue? Is the printer plugged in, powered on, and online? As with any troubleshooting, check your connections first.

Sometimes when nothing prints, you get a clue as to what the problem is. The printer may give you an “out of memory” error or something similar. Another possibility is that the printer will say “processing data” (or something similar) on its LCD display and nothing will print. It’s likely that the printer has run out of memory while trying to process the print job. If your printer is exhibiting these symptoms, it’s best to power the printer off and then power it back on.

Paper Jams

Laser printers today run at copier speeds. Because of this, their most common problem is paper jams. Paper can get jammed in a printer for several reasons. First, feed jams happen when the paper-feed rollers get worn (similar to feed jams in inkjet printers). The solution to this problem is easy: replace the worn rollers.

Another cause of feed jams is related to the drive gear of the pickup roller. The drive gear (or clutch) may be broken or have teeth missing. Again, the solution is to replace it. To determine if the problem is a broken gear or worn rollers, print a test page, but leave the paper tray out. Look into the paper-feed opening with a flashlight and see if the paper pickup roller(s) are turning evenly and don’t skip. If they turn evenly, the problem is probably worn rollers.

Worn exit rollers can also cause paper jams. These rollers guide the paper out of the printer into the paper-receiving tray. If they are worn or damaged, the paper may catch on its way out of the printer. These types of jams are characterized by a paper jam that occurs just as the paper is getting to the exit rollers. If the paper jams, open the rear door and see where the paper is located. If the paper is very close to the exit rollers, they are probably the problem.

The solution is to replace all of the exit rollers. You must replace all of them at the same time because even one worn exit roller can cause the paper to jam. Besides, they’re inexpensive. Don’t skimp on these parts if you need to have them replaced.

Paper jams can also be the fault of the paper. If your printer consistently tries to feed multiple pages into the printer, the paper isn’t dry enough. If you live in an area with high humidity, this could be a problem. We’ve heard some solutions that are pretty far out but that work (like keeping the paper in a Tupperware-type airtight container or microwaving it to remove moisture). The best all-around solution, however, is humidity control and keeping the paper wrapped until it’s needed. Keep the humidity around 50 percent or lower (but above 25 percent if you can, in order to avoid problems with electrostatic discharge).

Finally, a grounded metal strip called the static-eliminator strip inside the printer drains the transfer corona charge away from the paper after it has been used to transfer toner from the EP cartridge. If that strip is missing, broken, or damaged, the charge will remain on the paper and may cause it to stick to the EP cartridge, causing a jam. If the paper jams after reaching the transfer corona assembly, this may be the cause.

Blank Pages

There’s nothing more annoying than printing a 10-page contract and receiving 10 pages of blank paper from the printer. Blank pages are a somewhat common occurrence in laser printers. Somehow, the toner isn’t being put on the paper. There are three major causes of blank pages:

• The toner cartridge
• The transfer corona assembly
• The high-voltage power supply (HVPS)

All-Black Pages

Only slightly more annoying than 10 blank pages are 10 black pages. This happens when the charging unit (the charging corona wire or charging corona roller) in the toner cartridge malfunctions and fails to place a charge on the EP drum. Because the drum is grounded, it has no charge. Anything with a charge (like toner) will stick to it. As the drum rotates, all of the toner is transferred to the page and a black page is formed.

This problem wastes quite a bit of toner, but it can be fixed easily. The solution (again) is to replace the toner cartridge with a known, good manufacturer-recommended one. If that doesn’t solve the problem, then the HVPS is at fault (it’s not providing the high voltage that the charging corona needs to function).

Repetitive Small Marks or Defects

Repetitive marks occur frequently in heavily used (as well as older) laser printers. Toner spilled inside the printer may be causing the problem. It can also be caused by a crack or chip in the EP drum (this mainly happens with recycled cartridges), which can accumulate toner. In both cases, some of the toner gets stuck onto one of the rollers. Once this happens, every time the roller rotates and touches a piece of paper, it leaves toner smudges spaced a roller circumference apart.

The solution is relatively simple: Clean or replace the offending roller. To help you figure out which roller is causing the problem, the service manuals contain a chart like the one shown in Figure 12.14. (Some larger printers will also have the roller layout printed inside the service door.) To use the chart, place the printed page next to it. Align the first occurrence of the smudge with the top arrow. The next smudge will line up with one of the other arrows. The arrow it lines up with tells you which roller is causing the problem.

Vertical White Lines on the Page

Vertical white lines running down all or part of the page are a relatively common problem on older printers, especially ones that don’t see much maintenance. Foreign matter (more than likely toner) caught on the transfer corona wire causes this. The dirty spots keep the toner from being transmitted to the paper (at those locations, that is), with the result that streaks form as the paper progresses past the transfer corona wire.

The solution is to clean the corona wires. LaserJet Series II printers contain a small corona wire brush to help with this procedure. It’s usually a small, green-handled brush located near the transfer corona wire. To use it, remove the toner cartridge and run the brush in the charging corona groove on top of the toner cartridge. Replace the cartridge, and use the brush to remove any foreign deposits on the transfer corona. Be sure to put it back in its holder when you’re finished.

Vertical Black Lines on the Page

A groove or scratch in the EP drum can cause the problem of vertical black lines running down all or part of the page. Because a scratch is lower than the surface, it doesn’t receive as much (if any) of a charge as the other areas. The result is that toner sticks to it as though it were discharged. The groove may go around the circumference of the drum, so the line may go all the way down the page.

Another possible cause of vertical black lines is a dirty charging corona wire. A dirty charging corona wire prevents a sufficient charge from being placed on the EP drum. Because the charge on the EP drum is almost zero, toner sticks to the areas that correspond to the dirty areas on the charging corona.

The solution to the first problem is, as always, to replace the toner cartridge (or EP drum, if your printer uses a separate EP drum and toner). You can also solve the second problem with a new toner cartridge, but in this case that would be an extreme solution. It’s easier to clean the charging corona with the brush supplied with the cartridge.

Image Smudging

If you can pick up a sheet from a laser printer, run your thumb across it, and have the image come off on your thumb, you have a fuser problem. The fuser isn’t heating the toner and fusing it into the paper. This could be caused by a number of things—but all of them can be handled by a fuser replacement. For example, if the halogen light inside the heating roller has burned out, that would cause the problem. The solution is to replace the fuser. The fuser can be replaced with a rebuilt unit, if you prefer. Rebuilt fusers are almost as good as new ones, and some even come with guarantees. Plus, they cost less.

A similar problem occurs when small areas of smudging repeat themselves down the page. Dents or cold spots in the fuser heat roller cause this problem. The only solution is to replace either the fuser assembly or the heat roller.

Ghosting

Ghosting is what you have when you can see light images of previously printed pages on the current page. This is caused by one of two things: a broken cleaning blade or bad erasure lamps. A broken cleaning blade causes old toner to build up on the EP drum and consequently presents itself in the next printed image. If the erasure lamps are bad, then the previous electrostatic discharges aren’t completely wiped away. When the EP drum rotates toward the developing roller, some toner sticks to the slightly discharged areas.

If the problem is caused by a broken cleaner blade, you can replace the toner cartridge. If it’s caused by bad erasure lamps, you’ll need to replace them. Because the toner cartridge is the least expensive cure, you should try that first. Usually, replacing the toner cartridge will solve the ghosting problem. If it doesn’t, you will have to replace the erasure lamps.

Printer Prints Pages of Garbage

This has happened to everyone at least once. You print a one-page letter, but instead of the letter you have 10 pages of what looks like garbage (or garbled characters) or many more pages with one character per page come out of the printer. This problem comes from one of two different sources: the printer driver software or the formatter board.

Example Printer Testing: HP LaserJet

Now that we’ve defined some of the possible sources of problems with laser printers, let’s discuss a few of the testing procedures that you use with them. We’ll discuss HP LaserJet laser printers because they are the most popular brand of laser printer, but the topics covered here apply to other brands of laser printers as well.

We’ll look at two ways to troubleshoot laser printers: self-tests and error codes (for laser printers with LCD displays).

Self-Tests

You can perform three tests to narrow down which assembly is causing the problem: the engine self-test, the engine half self-test, or the secret self-test. These tests, which the printer runs on its own when directed by the user, are internal diagnostics for printers, and they are included with most laser printers.

Engine Self-Test The engine self-test tests the print engine of the LaserJet, bypassing the formatter board. This test causes the printer to print a single page with vertical lines running its length. If an engine self-test can be performed, you know that the laser print engine can print successfully. To perform an engine self-test, you must press the printer’s self-test button, which is hidden behind a small cover on the side of the printer (see Figure 12.15). The location of the button varies from printer to printer, so you may have to refer to the printer manual. Using a pencil or probe, press the button, and the print engine will start printing the test page.

Half Self-Test A print engine half self-test is performed the same way as the self-test, but you interrupt it halfway through the print cycle by opening the cover. This test is useful in determining which part of the print process is causing the printer to malfunction. If you stop the print process and part of a developed image is on the EP drum and part has been transferred to the paper, you know that the pickup rollers, registration rollers, laser scanner, charging roller, EP drum, and transfer roller are all working correctly. You can stop the half self-test at various points in the print process to determine the source of a malfunction.

Secret self-test To activate this test, you must first put the printer into service mode. To accomplish this, turn on the printer while simultaneously holding down the On Line, Continue, and Enter buttons (that’s the first secret part, because nobody knows it unless somebody tells them). When the screen comes up blank, release the keys and press, in order, Continue and then Enter. The printer will perform an internal self-test and then display 00 READY. At this point, you are ready to initiate the rest of the secret self-test. Take the printer offline by pressing the On Line button, press the Test button on the front panel, and hold the button until you see the 04 Self Test message. Then release the Test button. This will cause the printer to print one self-test page. (If you want a continuous printout, instead of releasing the Test button at the 04 Self Test message, keep holding the Test button. The printer will print continuous self-test pages until you power it off or press On Line or until it runs out of paper.)

Troubleshooting Tips for HP LaserJet Printers

Printer technicians usually use a set of troubleshooting steps to help them solve HP LaserJet printing problems. Let’s detail each of them to bring our discussion of laser printer troubleshooting to a close:

1. Is the exhaust fan operational? This is the first component to receive power when the printer is turned on. If you can feel air coming out of the exhaust fan, this confirms that AC voltage is present and power is turned on, that +5VDC and +24VDC are being generated by the AC power supply (ACPS), and that the DC controller is functional. If there is no power to the printer (no lights, fan not operating), the ACPS is at fault. Replacement involves removing all printer covers and removing four screws. You can purchase a new ACPS module, but it is usually cheaper to replace it with a rebuilt unit.

2. Do the control panel LEDs work? If so, the formatter board can communicate with the control panel. If the LEDs do not light, it could mean that the formatter board is bad, the control panel is bad, or the wires connecting the two are broken or shorting out.
3. Does the main motor rotate at power up? Turn off the power. Remove the covers from the sides of the printer. Turn the printer back on and carefully watch and listen for main motor rotation. If you see and hear the main motor rotating, this indicates that a toner cartridge is installed, all photo sensors are functional, all motors are functional, and the printer can move paper (assuming that there are no obstructions).
4. Does the fuser heat lamp light after the main motor finishes its rotation? You will need to remove the covers to see this. The heat lamp should light after the main motor rotation and stay lit until the control panel says 00 Ready.
5. Can the printer perform an engine test print? A sheet of vertical lines indicates that the print engine works. This test print bypasses the formatter board and indicates whether the print problem resides in the engine. If the test print is successful, you can rule out the engine as a source of the problem. If the test print fails, you will have to troubleshoot the printer further to determine which engine component is causing the problem.
6. Can the printer perform a control panel self-test? This is the final test to ensure printer operation. If you can press the Test Page control panel button and receive a test printout, this means that the entire printer is working properly. The only possibilities for problems are outside the printer (interfaces, cables, and software problems).

Managing the Print Spooler

The print spooler is a service that formats print jobs in a language that the printer understands. Think of it as a holding area where the print jobs are prepared for the printer. In Windows, the spooler is a service that’s started automatically when Windows loads.

If jobs aren’t printing and there’s no apparent reason why, it could be that the print spooler has stalled. To fix the problem, you need to stop and restart the print spooler. Exercise 12.3 walks you through stopping and restarting the spooler in Windows 7.

If you have a different version of Windows, the steps to stop and restart the spooler are the same as in Exercise 12.3; the only difference might be in how you get to Computer Management.

Printing a Test Page

If your printer isn’t spitting out print jobs, it may be a good idea to print a test page and see if that works. The test page information is stored in the printer’s memory, so there’s no formatting or translating of jobs required. It’s simply a test to make sure that your printer hears your computer.

When you install a printer, one of the last questions it asks is if you want to print a test page. If there’s any question, go ahead and do it. If the printer is already installed, you can print a test page from the printer’s Properties window (right-click the printer and choose Printer Properties). Just click the Print Test Page button and it should work. If nothing happens, double-check your connections and stop and restart the print spooler. If garbage prints, there is likely a problem with the printer or the print driver.

No Connectivity

Let’s start with the most dire situation: no connectivity. Taking a step back to look at the big picture, think about all of the components that go into networking. On the client side, you need a network card and drivers, operating system, protocol, and the right configuration. Then you have a cable of some sort or a wireless connection. At the other end is a switch or wireless router. That device connects to other devices, and so forth. The point is, if someone is complaining of no connectivity, there could be one of several different things causing it. So start with the basics.

The most common issue that prevents network connectivity on a wired network is a bad or unplugged patch cable. Cleaning crews and the rollers on the bottoms of chairs are the most common threats to patch cables. In most cases, wall jacks are placed 4 to 10 feet away from the desktop. The patch cables are normally lying exposed under the user’s desk, and from time to time damage is done to the cable or it’s inadvertently snagged and unplugged. Tightly cinching the cable while tying it up out of the way is no better a solution. Slack must be left in the cable to allow for some amount of equipment movement and to avoid altering the electrical characteristics of the cable. When you troubleshoot connectivity, start with the most rudimentary explanations first. Make sure that the patch cable is tightly plugged in, and then look at the card and check if any lights are on. If there are lights on, use the NIC’s documentation to help troubleshoot. More often than not, shutting down the machine, unplugging the patch and power cables for a moment, and then reattaching them and rebooting the PC will fix an unresponsive NIC.

If you don’t have any lights, you don’t have a connection. It could be that the cable is bad or that it’s not plugged in on the other side, or it could also be a problem with the NIC or the connectivity device on the other side. Is this the only computer having problems? If everyone else in the same area is having the same problem, that points to a central issue.

Most wireless network cards also have indicators on them that can help you troubleshoot. For example, a wireless card might have a connection light and an activity light, much like a wired network card. On one particular card we’ve used, the lights will alternate blinking if the card isn’t attached to a network. Once it attaches, the connection light will be solid and the link light will blink when it’s busy. Other cards may operate in a slightly different manner, so be sure to consult your documentation.

If you don’t have any lights, try reseating your cables and rebooting. It might also help to reseat the card. If you’re using a USB or ExpressCard wireless adapter, this is pretty easy. If it’s inside your desktop, it will require a little surgery. If it’s integrated into your laptop, you could have serious issues. Try rebooting first. If that doesn’t help, see if you can use an expansion NIC and make that one light up.

Let’s assume that you have lights and that no one else is having a problem. (Yes, it’s just you.) This means that the network hardware is probably okay, so it’s time to check the configuration. Open a command prompt, type IPCONFIG, and press Enter. You should get an IP address. (If it starts with 169.254.x.x, that’s an APIPA address. We’ll talk about those next.) If you don’t have a valid IP address, that’s the problem.

If you do have a valid IP address, it’s time to see how far your connectivity reaches. With your command prompt open, use the PING command to ping a known, remote working host. If that doesn’t work, start working backward. Can you ping the outside port of your router? The inside port? A local host? (Some technicians recommend pinging your loopback address first with PING 127.0.0.1 and then working your way out to see where the connectivity ends. Either way is fine. The advantage to starting with the loopback is that if it doesn’t work, you know nothing else will either.) Using this methodology, you’ll be able to figure out where your connectivity truly begins and ends.

APIPA and Link Local Addresses

As we talked about in Chapter 7, “Introduction to TCP/IP,” Automatic Private IP Addressing (APIPA) is a service that auto-configures your network card with an IP address. APIPA kicks in only if your computer is set to receive an IP address from the Dynamic Host Configuration Protocol (DHCP) server and that server doesn’t respond. You can always tell an APIPA address because it will be in the format of 169.254.x.x.

When you have an APIPA address, you will be able to communicate with other computers that also have an APIPA address but not with any other resources. The solution is to figure out why you’re not getting an answer from the DHCP server and fix that problem.

Link local addresses are the IPv6 version of APIPA, and link local addresses always start with fe80:: (they are in the fe80::/10 range).They will work to communicate with computers on a local network, but they will not work through a router. If the only IP address that your computer has is a link local one, you’re not going to communicate outside of your network. The resolution is the same as it is for APIPA.

IP Address Conflicts

Every host on a network needs to have a unique IP address. If two or more hosts have the same address, communication problems will occur. The good news is that nearly every operating system today will warn you if it detects an IP address conflict with your computer. The bad news is it won’t fix it by itself.

The communication problems will vary. In some cases, the computer will seem nearly fine, with intermittent connectivity issues. In others, it will appear as if you have no connectivity.

The most common cause of this is if someone configures a computer with a static IP address that’s part of the DHCP server’s range. The DHCP server, not knowing that the address has been statically assigned somewhere, doles out the address and now there’s a conflict. Rebooting the computer won’t help, and neither will releasing the address and getting a new lease from the DHCP server—it’s just going to hand out the same address again because it doesn’t know that there’s a problem.

As the administrator, you need to track down the offending user. A common way to do this is to use a packet sniffer to look at network traffic and determine the computer name or MAC address associated with the IP address in question. Most administrators don’t keep network maps of MAC addresses, but everyone should have a network map with hostnames. If not, it could be a long, tedious process to check everyone’s computer to find the culprit.

Limited or Local Connectivity

In a way, limited connectivity problems are a bit of a blessing. You can immediately rule out client-side hardware issues because they can connect to some resources. You just need to figure out why they can’t connect to others. This is most likely caused by one of two things: a configuration issue or a connectivity device (such as a router) problem.

Check the local configuration first. Use IPCONFIG /ALL to ensure that the computer’s IP address, subnet mask, and default gateway are all configured properly. After that, use the ping utility to see the range of connectivity. In situations like this, it’s also good to check with other users in the area. Are they having the same connectivity issues? If so, it’s more likely to be a central problem rather than one with the client computer.

Intermittent Connectivity

Under this heading, we’re going to consider intermittent connectivity, slow transfer speeds, and low radio frequency (RF) signals because they are all pretty similar.

On a wired network, if you run into slow speeds or intermittent connectivity, it’s likely a load issue. There’s too much traffic for the network to handle, and the network is bogging down. (You obviously don’t need to worry about RF signals on a wired network.) Solutions include adding a switch, replacing your hubs with switches, and even creating virtual LANs (VLANs) with switches. If the network infrastructure is old (for example, if it’s running on Category 3 cable or you only have 10Mbps switches), then it might be time for an upgrade.

Wireless networks can get overloaded too. It’s recommended that no more than 30 or so client computers use one wireless access point (WAP) or wireless router. Any more than that can cause intermittent access problems. The most common reason that users on wireless networks experience any of these issues though is distance. The further away from the WAP the user gets, the weaker the signal becomes. When the signal weakens, the transfer rates drop dramatically. For example, the signal from an 802.11g wireless router has a maximum range of about 300 feet barring any obstructions. At that distance though, 802.11g will support transfer rates of only 6Mbps—far less than the 54Mbps the users think they’re getting! The solution here is to move closer or install more access points. Depending on the configuration of your working environment, you could also consider adding a directional antenna to the WAP. It will increase the distance the signal travels, but only in a limited direction.

SSID Not Found

This is obviously a wireless problem, because wired networks don’t use service-set identifiers (SSIDs). If a client can’t find an SSID for a network it had previously joined, it’s possible that the router’s SSID has been changed. If you’re going to change an SSID, be sure to alert all users or technicians who might be affected. A second potential cause could be that the router is configured to not broadcast SSIDs. Some administrators will stop this broadcast, believing that doing so will increase the network security. It really doesn’t, because any semi-decent hacker with a wireless packet sniffer will pick it up—what it does best, though, is make it difficult for legitimate users to join the network. With all of that said, CompTIA A+ exam objectives list disabling SSID broadcasts as a security measure, so be aware of that. Just don’t expect it to secure the wireless network in real life.

A third potential cause is that the user’s computer is too far out of range. Get closer to the access point or wireless router and the signal should appear.

Hardware and Cabling Tools

We covered several different types of cables and their properties in Chapter 6, “Networking Fundamentals.” Here we will look at some tools that can be used to make or test network cables as well as a few tools to troubleshoot network connectivity issues.

Crimper

A crimper is a very handy tool for helping you put connectors on the end of a cable. Most crimpers will be a combination tool that strips and snips wires as well as crimps the connector on to the end. Figure 12.21 shows you one of these tools. You can also buy tools that are just cable strippers and cable snippers, but usually the point of cutting and stripping a cable is to put a connector on the end of it, so why not just get a crimper that does it all?

Multimeter

Multimeters are versatile electronic measuring tools. A multimeter can measure voltage, current, and resistance on a wire. There are a wide variety of types and qualities on the market, everywhere from economical $10 versions to ones that cost several thousand dollars. Figure 12.22 shows a basic multimeter.

Toner Probe

If you need to trace a wire in a wall from one location to another, a toner probe is the tool for you. Shown in Figure 12.23, it consists of two pieces: a tone generator and a probe. Because it’s so good at tracking, you will sometimes hear this referred to as a “fox and hound.”

To use a toner probe, attach one end to one end of the cable, such as the end at the computer. Then go to the patch panel with the other end of the probe to locate the cable. These are lifesavers when the cables are not properly labeled.

Cable Tester

Cable testers are indispensable tools for any network technician. Usually you would use a cable tester before you install a cable to make sure it works. Of course, you can test them after they’ve been run as well. A decent cable tester will tell you the type of cable, and more elaborate models will have connectors for multiple types of cables. Figure 12.24 shows a TRENDnet cable tester.

Punch-Down Tool

If you’re working on a larger network installation, you might use a punch-down tool. It’s not a testing tool but one that allows you to connect (that is, punch down) the exposed ends of a wire into wiring harnesses, such as a 110 block (used many times in connectivity closets to help simplify the tangled mess of cables). Figure 12.25 shows the tool and its changeable bit.

Loopback Plug

A loopback plug is for testing the ability of a network adapter to send and receive. The plug gets plugged into the NIC, and then a loopback test is performed using troubleshooting software. You can then tell if the card is working properly or not. Figure 12.26 shows an Ethernet loopback plug, but they are made for fiber-optic NICs as well.

Wireless Locator

The one hardware tool that we didn’t talk much about earlier is a wireless locator. Specific tools for locating Wi-Fi networks and analyzing their traffic are indispensable today. A wireless locator or a Wi-Fi analyzer can be either a handheld hardware device, such as the one shown in Figure 12.27, or specialized software that is installed on a laptop and whose purpose is to detect and analyze Wi-Fi signals. Anyone interested in wardriving will definitely have one of these, but they’re also handy for locating wireless hot spots.

Software Commands

Troubleshooting networks often involves using a combination of hardware tools and software commands. Usually, the software commands are easier to deal with because you don’t need to dig around physically in a mess of wires to figure out what’s going on. The downside to the software commands is that there can be a number of options that you need to memorize. In the following sections, we’ll cover the networking command-line tools, which you are expected to know for this exam: PING, IPCONFIG/IFCONFIG, TRACERT, NETSTAT, NBTSTAT,NET, NETDOM, and NSLOOKUP.

PING Command

The PING command is one of the most useful commands in the TCP/IP protocol. It sends a series of packets to another system, which in turn sends back a response. This utility can be extremely useful for troubleshooting problems with remote hosts. Pings are also called ICMP echo requests/replies because they use Internet Control Message Protocol (ICMP).

The PING command indicates whether the host can be reached and how long it took for the host to send a return packet. Across wide area network links, the time value will be much larger than across healthy LAN links.

The syntax for PING is ping hostname or ping IP address. Figure 12.28 shows what a ping should look like.

As you can see, by pinging with the hostname, we found the host’s IP address thanks to DNS. The time is how long in milliseconds it took to receive the response. On a LAN, you want this to be 10 milliseconds (ms) or less, but 60ms to 65ms for an Internet ping isn’t too bad.

There are several options for the PING command, and you can see them all by typing ping /? at the command prompt. Table 12.6 lists some of the more useful ones.

Option	Function
-t	Persistent ping. Will ping the remote host until stopped by the client (by using Ctrl+C).
-n count	Specifies the number of echo requests to send.
-l size	Specifies the packet size to send.
ping -4 / ping -6	Use either the IPv4 or IPv6 network explicitly.

IPCONFIG Command

With Windows-based operating systems, you can determine the network settings on the client’s network interface cards, as well as any that a DHCP server has leased to your computer, by typing the following at a command prompt: IPCONFIG /ALL.

IPCONFIG /ALL also gives you full details on the duration of your current lease. You can verify whether a DHCP client has connectivity to a DHCP server by releasing the client’s IP address and then attempting to lease an IP address. You can conduct this test by typing the following sequence of commands from the DHCP client at a command prompt:

ipconfig /release
ipconfig /renew

IPCONFIG is one of the first tools to use when experiencing problems accessing resources because it will show you whether an address has been issued to the machine. If the address displayed falls within the 169.254.x.x category, this means that the client was unable to reach the DHCP server and has defaulted to Automatic Private IP Addressing (APIPA), which will prevent the network card from communicating outside its subnet, if not altogether. Table 12.7 lists useful switches for IPCONFIG.

Switch	Purpose
/ALL	Shows full configuration information
/RELEASE	Releases the IP address, if you are getting addresses from a Dynamic Host Configuration Protocol (DHCP) server
/RELEASE6	Releases the IPv6 addresses
/RENEW	Obtains a new IP address from a DHCP server
/RENEW6	Obtains a new IPv6 address from a DHCP server
/FLUSHDNS	Flushes the Domain Name System (DNS) server name resolver cache

Figure 12.29 shows output from IPCONFIG, and Figure 12.30 shows you the output from IPCONFIG /ALL.

In Exercise 12.4, you will renew an IP address on a Windows 7/Vista system within the graphical interface. Exercise 12.5 shows you how to renew your lease from the command line.

While Windows provides this interface to troubleshoot connection problems, some administrators still prefer the reliability of a command-line interface. Exercise 12.5 shows you how to perform a similar action using the command line.

TRACERT Command

TRACERT (trace route) is a Windows-based command-line utility that enables you to verify the route to a remote host. Execute the command TRACERT hostname, where hostname is the computer name or IP address of the computer whose route you want to trace. Tracert returns the different IP addresses the packet was routed through to reach the final destination. The results also include the number of hops needed to reach the destination. If you execute the TRACERT command without any options, you see a help file that describes all of the TRACERT switches.

This utility determines the intermediary steps involved in communicating with another IP host. It provides a road map of all the routing an IP packet takes to get from host A to host B.

Timing information from TRACERT can be useful for detecting a malfunctioning or overloaded router. Figure 12.31 shows what a TRACERT output looks like. In addition to TRACERT, there are many graphical third-party network-tracing utilities available on the market.

NETSTAT Command

The NETSTAT command is used to check out the inbound and outbound TCP/IP connections on your machine. It can also be used to view packet statistics, such as how many packets have been sent and received and the number of errors.

When used without any options, the NETSTAT command produces output similar to what you see in Figure 12.32, which shows all of the outbound TCP/IP connections.

There are several useful command-line options for NETSTAT, as shown in Table 12.8.

Option	Function
-a	Displays all connections and listening ports.
-b	Displays the executable involved in creating each connection or listening port. In some cases, well-known executables host multiple independent components, and in these cases the sequence of components involved in creating the connection or listening port is displayed. In this case, the executable name is in brackets at the bottom [ ]. At the top is the component it called, in sequence, until TCP/IP was reached. Note that this option can be time consuming, and it will fail unless you have sufficient permissions.
-e	Displays Ethernet statistics. This may be combined with the -s option.
-f	Displays fully qualified domain names (FQDNs) for foreign addresses.
-n	Displays addresses and port numbers in numerical form.
-o	Displays the owning process ID associated with each connection.
-p proto	Shows connections for the protocol specified by proto; proto may be any of the following: TCP, UDP, TCPv6, or UDPv6. If used with the -s option to display per-protocol statistics, proto may be IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, or UDPv6.
-r	Displays the routing table.
-s	Displays per-protocol statistics. By default, statistics are shown for IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, and UDPv6; the -p option may be used to specify a subset of the default.

NBTSTAT Command

NBTSTAT is a command that shows NetBIOS over TCP/IP information. While not used as often as other entries in this category, it can be useful when trying to diagnose a problem with NetBIOS name resolution. The /? parameter can be used to see the available switches. Sample output from this command is shown in Figure 12.33.

NET Command

Depending on the version of Windows you are using, NET can be one of the most powerful commands at your disposal. While all Windows versions include a NET command, its capabilities differ based on whether it is used on a server or workstation and the version of the operating system.

While always command-line based, this tool allows you to do almost anything that you want with the operating system.

Table 12.9 shows common NET switches.

These commands are invaluable troubleshooting aids when you cannot get the graphical interface to display properly. You can also use them when interacting with hidden ($) and administrative shares that do not appear within the graphical interface.

The NET command used with the SHARE parameter enables you to create shares from the command prompt, using this syntax:

NET SHARE <share_name>=<drive_letter>:<path>

To share the C:EVAN directory as SALES, you would use the following command:

NET SHARE SALES=C:EVAN

You can use other parameters with NET SHARE to set other options. Table 12.10 summarizes the most commonly used parameters, and Exercise 12.6 will give you some experience with the NET SHARE command.

The NET /? command is basically a catch-all help request. It will instruct you to use the NET command in which you are interested for more information.

NETDOM Command

NETDOM is a tool first included with Windows Server 2008 that provides Active Directory management capabilities, specifically domain and trust management. In order to run NETDOM, you must have administrative privileges. NETDOM allows an administrator to perform the following tasks:

• Rename a computer that is a member of a domain.
• Join a client computer (Windows XP or newer) to a Windows domain.
• Manage computer accounts within a domain, such as adding or removing computers, changing the organizational unit (OU) for the computer, or moving a computer from one domain to another.
• Establishing and managing trust relationships between domains.

Most of the actions for which NETDOM is used are relatively advanced Windows Server administrator functions, so it’s a bit surprising to see this command on the A+ exam. For the purposes of the exam, think of NETDOM as the command you would use to manage computer accounts (not user accounts) and membership in domains.

NSLOOKUP Command

One of the key things that must take place to use TCP/IP effectively is that a hostname must resolve to an IP address—an action usually performed by a DNS server.

NSLOOKUP is a command that enables you to verify entries on a DNS server. You can use the NSLOOKUP command in two modes: interactive and noninteractive. In interactive mode, you start a session with the DNS server in which you can make several requests. In noninteractive mode, you specify a command that makes a single query of the DNS server. If you want to make another query, you must type another noninteractive command.

To start nslookup in interactive mode (which is what most admins use because it allows them to make multiple requests without typing NSLOOKUP several times), type NSLOOKUP at the command prompt and press Enter. You will receive a greater than prompt (>) and can then type in the command that you want to run. You can also type HELP or ? to bring up the list of possible commands, as shown in Figure 12.36. To exit nslookup and return to a command prompt, type EXIT and press Enter.

To run NSLOOKUP in noninteractive mode, you would use the NSLOOKUP command option you want to run at the command prompt. Examples would be NSLOOKUP /SET TIMEOUT=<3> or NSLOOKUP /VIEW:DOMAIN.