Networking Device Interfaces and Tools | CompTIA Tech+ Course Clip

By Microsoft MVP and MCT · Pluralsight Author

Published December 10, 2024 · Updated January 15, 2026 · Learning & Credentials

This CompTIA Tech+ course clip is from my full Tech+ course on Infrastructure: Foundations of IT Infrastructure and Networking Technologies for the certification exam.

Check out the full course

Video Summary

  • RJ45 Ethernet Connectors: Standard for wired networks, easy to use, and available in various categories with Cat 8 supporting up to 40 Gbps.
  • Fiber Connectors (SFP): Used for high-speed networking in enterprise environments, supporting speeds from 1 Gbps to 100 Gbps, but more expensive than Ethernet cables.
  • Crimpers: Tools for creating custom-length Ethernet cables by cutting and attaching RJ45 connectors securely.
  • Cable Testers: Devices to check if all pins in a network cable are correctly connected, essential for troubleshooting custom-made cables.
  • Using a Cable Tester: Connect both ends of the cable to the tester; matching lights on both sides indicate a good cable, while mismatched lights indicate a problem

For more information, read the transcript blog below, or watch the video above!

Video Transcript

And if there’s one stereotype that is true, it’s that everyone working in IT has a box of cables at home, including one of each type of cable that has existed for the past 20 years, just in case. In this module, we will learn about the different types of connections used to connect both PCs to a network as well as peripherals to a PC. Let’s start by learning about network connections and tools.

We’ll begin with the most common network cable, the RJ45. This type of connector is used for Ethernet networking, which is the standard for wired networks. The RJ45 connector has eight pins that are used to transmit and receive data. This type of connector is used for both home and business networks. One of the great things about RJ45 connectors is how easy they are to use. It’s essentially a plug-and-play device; you just connect one end to your computer and the other to a router, and you’re good to go. Ethernet cables come in multiple categories, from Category 1 all the way to Category 8.

Let’s talk about the four latest ones without going into too much detail. While they all use the same RJ45 connector, the main differences between Ethernet cable categories are the speed each category supports, with Cat 8 designed for up to 40 Gbps, which is significantly higher than older categories such as Cat 6. We also have bandwidth, as newer cables like Cat 8 offer higher bandwidth, meaning they can carry more data at the same time, which is crucial for data-heavy applications. Another differentiator is distance; the longer the cable, the more speed you can lose. Some cables, like Cat 8, have amazing speed but only for 30 meters, while Cat 7 can maintain the same speed for 100 meters.

Depending on your needs, the highest category might not always be the best. Finally, we have shielding. As you move up from Cat 6, where shielding is optional, to Cat 8, the cables come with mandatory shielding to fit that standard. This helps a lot, especially to reduce interference in high-speed or dense network environments. You do not need to know all of these by heart for the Tech Plus exam, but I still wanted to show you the differences between categories. If you have a few Ethernet cables lying around at home, take a look at them; they will tell you the category.

Next up, another networking connector is the fiber connector, Small Form-Factor Pluggable (SFP) connector. This connector is a compact, hot-swappable transceiver module used in networking to interface with fiber optic or copper cabling. Depending on the type of SFP used, you can achieve varying data transfer speeds and distances, from 1 Gbps with basic SFP modules up to 100 Gbps with newer modules.

However, they are much more expensive than Ethernet cables and are often only used between networking devices, such as between a router and a switch. If we look at a router, you can see the RJ45 and the SFP side by side, as well as the connection where it goes. If you look closely at the image on the right side, you will see that my SFP port has a maximum of 10 Gbps, whereas my Ethernet, which is currently plugged in, has a maximum of 2.5 Gbps. Again, 2.5 Gbps is more than enough for most household devices, but for an enterprise where you might have 100 clients that need to connect from a switch to a router to the internet, having that SFP connector and enabling higher speeds between networking devices can make all the difference.

Now let’s talk about some networking tools. The first one we will discuss is the crimper. The crimper is used when you want to make your own Ethernet connections and customize the length of the cable. They allow you to cut the Ethernet cable to the exact length you need and then connect it. After you cut the cable to the right length, you can use the crimper to press your RJ45 connector and connect it to the cable, ensuring that the metal from the connector touches the copper wires. This way, you make sure that all the data transmits correctly and that the connector will not easily pull off.

Our next troubleshooting tool is the cable tester. The cable tester is a simple tool that ensures all the pins (pin 1 through pin 8) of a network cable are connected correctly. This is especially useful if you cut your own Ethernet cables and connect them using the crimper. It happened to me when I cabled around my house; one of the cables was giving errors, and my device would not work properly. After using the cable tester, I figured out it was just a bad connection; I had reversed two different pins on the Ethernet cable, and that can happen. I have a very simple one that we will look at in just a few seconds, but more advanced and professional cable testers can also help with things such as interference and signal loss measurements.

Now let’s take a look at a cable tester in action. The concept of a cable tester is pretty simple. You have two different pieces, two sides, and you plug the cable you want to test into both sides of the tester. The cable tester will send data on each pin of the eight pins of the cable. Remember, the RJ45 connector has eight pins. As long as the lights on the left side and the right side light up the same number all the time, it means the cable is good. Let me try with a bad cable. I have a cable here that I sabotaged a little bit. If we put it in the tester, you will see that it only goes to seven, and the eighth pin never lights up. This is because I cut it, but this is how you would see a broken cable or if the cable was not connected right. For example, if you crimped it and didn’t put the cables in the right order, you would see, say, number five light up on the left while number one lights up on the right. You really need to make sure that the numbers on the left and right light up at the same time so you know all the pins are well connected and in the right order.