Common Networking Tools – CompTIA A+ 220-801: 2.10

| December 2, 2012

If you’re managing a network, then you’ll need to maintain a good toolkit of network devices. In this video, you’ll learn about crimpers, multimeters, toner probes, cable testers, loopback plugs, and punch down tools.

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Review Quiz: Common Networking Tools

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A good all-around tool for any network professional is a pair of crimpers. These crimpers are designed to take the connector on the end of a cable and the wires and crimp them together or push them together. And this works for things like coaxial cable. You can use this on twisted pair. There are different types of crew members for different types of network connectors.

This is usually the last thing you’ll do. Once you run the wire and you’ve got the wires on each side, both need connectors on them. You would grab your pair of crimpers to add those connectors.

When you create the end of the cable, it’s a pretty permanent process. You are taking these metal prongs that are inside of the connectors themselves and pushing those prongs into the insulation and through, all the way to the copper that’s inside of that. You’re also tightening up the cable inside of the connector so that it can’t accidentally pull out of the end of that connection.

If you look closely at a connector, you’ll see those metal prongs that are inside of it. They’re very sharp. In they’re designed, once you crimp it, those are pushed upwards and into the cable, that is then inside of the connector.

You can see an example of it right there. Notice there is usually this connection at the end that is pushed up so that it tightly holds that cable in place.

Another must have instrument for any computer professional is a multimeter. A multimeter is designed to tell you everything about voltage and current and resistance. So you can start troubleshooting to determine what might be going on with the power inside of your computer system. You might also see this referred to as a VOM. That stands for a Volt-Ohm meter.

There are many different kinds of multimeters. This one happens to be a digital multimeter. But you can also find analog multimeters as well. And in the United States, you can find them as low as $10. Of course, very sensitive versions of multimeters can go up into the hundreds of dollars.

These are relatively easy to use. You simply have these two probes. And you set your settings on the multimeter. And you put those two probes on a connection.

So you can determine if there is continuity. You can look at voltage. You can see resistance and much more.

You do want to be very careful when using these. Since you’re going to be around power sources generally when you’re using a multimeter, make sure you know what you’re doing. You don’t want to mess around when it comes to dealing with power.

If you need to check to see if the voltage that’s in a wall connection is correct, you can of course use your multimeter to determine the exact voltage amount coming out of that wall outlet. And of course, a lot of the power inside of your computer is direct current. So you can of course set your multimeter to DC and look at the voltages coming off of your power supply. Or look at the voltages on the battery that’s used to maintain the power to your CMOS.

Your multimeter can also be used outside of your computer to check continuity. You can see if a cable is working properly between one end and the other or to check your fuses to make sure that none of them have blown.

If there are a lot of network connections inside of your environment, you may want to think about investing in a toner and a probe. These will allow you to track where a wire is going, especially if that wire is going through the wall into another room.

These are very easy to use. You have a tone generator that you would connect to a wire. Sometimes they have an RJ45 or an RJ11 connection in them. Or they might have these alligator clips at the end, that you would simply clip onto an existing wire. And that sends a tone through the wire.

The other part of the equation is this inductive probe. This probe has a little speaker on it. So it can listen in and tell you if you’re getting close to the wire that might have that tone on it that’s being generated by our tone generation device.

Because it’s inductive, we don’t have to physically touch the copper of the cable. We just have to get close. So if you simply go from wire to wire with your inductive probe, you’ll notice the tone gets louder and louder. And eventually you’ll find exactly the wire that that tone is going through.

If you need to do more advanced troubleshooting of your wiring, you may need something like one of these advanced cable testers. They’re able to give you a lot of different statistics. For instance, they can give you near end crosstalk. It can determine how much interference is occurring between wires that are closest to the transmitting end or the near end.

There’s also far end crosstalk, which is the same information. But it’s measured as far away from the transmitter as possible. There’s also alien crosstalk, AXT, which is where we are getting interference that are not coming from inside of our cable. They’re coming from somewhere else. It’s alien to the cable we happen to be using.

And there’s also an attenuation to crosstalk ratio, or an ACR, which is the difference between the insertion loss and the near end crosstalk. You sometimes see this referred to as the signal to noise ratio. So we can determine just how effectively this wire is working.

If you’re testing a piece of equipment or a network connection, it might be useful to have a loopback plug. These loopback plugs can also be useful if there’s an application that needs to think it’s on the network, but you’re not currently connected to a network connection.

There are loopback plugs for serial connections. So if you’re plugging into the serial port on the back of your computer, there’s probably a 9-pin connection. And on some older computers, you may even find a 25-pin connection for serial.

But most often, we are using these loopback plug connections for network connections. We have our ethernet network. We have a T1 wide area network. Maybe it’s a fiber connection. And we need to loopback that information so that it leaves a piece of the equipment and comes right back into that equipment again.

Keep in mind that these are not cross-over cables. A cross-over cable for ethernet is designed to directly connect two devices together. A loopback plug isn’t going anywhere. It’s sending information out of the device and turning it around right there, before it hits another device, and comes right back in the same way it left.

That way you’re able to send information out a port and receive information into that same port. And those two things should match, because we’re simply looping them back.

You generally don’t need a loopback plug unless you’ve run into a nasty problem but you can’t troubleshoot otherwise. Some people don’t have any loopback plugs. And when it comes time to do the heavy troubleshooting, they have to now scramble around to try to find one.

And you usually would need one for every thing that you have. If you have fiber, if you have ethernet connections, T1 connections, you need to have the right kind of loopback plug for the right kind of connection.

And in my case, I like to make my own. That’s a great website,, where you can make an ethernet cable, a cross-over cable, a modem, a null modem, and a Cisco console just in one single set of adapters. It makes it very, very efficient. And that way you know you will always have an ethernet cross-over cable and an ethernet loopback cable with you at all times.

If you’re working with the wiring in your infrastructure, then you may be using a punch-down tool to fasten all of those wires into a single block. And at that point, we can use that block to cross connect them to other wires that might be going somewhere else.

This can be a pretty tedious process because you’re going to every single wire. Sometimes you can get a punch-down tool that will do multiple wires at exactly the same time, to hopefully shorten the process. But still, there are a lot of wires in your organization.

This is something that’s pretty efficient. When you punch it down, it not only connects it into the punch-down block, but it also trims it off, so that you can very easily get rid of all the excess wiring, just with one single force.

Here’s an example of what you would see on a 110 block. These have already been punched down. And you can see here on the top are connectors that are waiting to have wires added to them. We would place the wire right on top and then use the punch-down block to push it into the connection.

And you can see that those very short connectors there are breaking into the outside of the cable so they can touch the copper on the inside. This is very similar to placing those standard modular connectors onto the cable that’s plugging into your computer. But instead of it going into a modular connector, we’re placing it into these connections on a punch-down block.

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Category: CompTIA A+ 220-801

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