CompTIA A+ Rapid Review: Networking

  • 4/15/2013

Objective 2.10: Given a scenario, use appropriate networking tools

Network technicians use several different tools to create cables, wire networks, and troubleshoot problems. This objective expects you to know about many of these tools, including the scenarios when these tools are appropriate to use.

Exam need to know...

  • Crimper

    For example: What is the primary purpose of a crimper?

  • Multimeter

    For example: What setting on a multimeter is used to check for cable breaks?

  • Toner probe

    For example: What is the primary purpose of a toner probe?

  • Cable tester

    For example: What information is provided by a cable tester?

  • Loopback plug

    For example: What is tested with a loopback plug?

  • Punchdown tool

    For example: Where is a punchdown tool used?


Network technicians are often tasked with creating cables. The job is much easier when technicians have the correct tools, such as wire crimpers.

True or false? A crimper is used to secure an RJ-45 connector onto a twisted-pair cable.

Answer: True. Crimpers are used to secure connectors onto cables. The wires are placed into the connector in the proper location, and the crimper squeezes the connector onto the cable.

There are many specific types of crimpers, including those used to crimp RJ-45 cables onto twisted-pair cables. Other crimpers are available for other types of cables, and some can crimp multiple types of connectors. For example, crimpers are available to secure RJ-11 connectors to phone cables and to secure RJ-45 connectors onto network cables.


Multimeters include two probes and are used to measure voltage, amperage, and resistance. These are commonly used to measure voltages from power supplies but have a different use with networks.

True or false? Multimeters are commonly used to measure amperage going through network cables.

Answer: False. Multimeters are rarely used to measure amperage (or current) through network cables.

Most multimeters include a continuity checker that can be used to verify that a cable doesn’t have any breaks. This setting measures when a cable has zero resistance or is continuous from end to end. When you select the continuity check function and touch both probes together, the multimeter beeps, indicating that there is a continuous connection. Similarly, when you touch both ends of a cable with each of the probes, it beeps if the cable is good. If you don’t hear a beep, you know the cable has a break.

Toner probe

A toner probe includes two components. One component creates a tone, and the second component has a speaker to hear the tone.

True or false? A toner probe is used to verify that a NIC is operational.

Answer: False. A toner probe is used to trace network cables between two different locations.

For example, if you have 50 cables going from an office to a wiring closet, you sometimes need to identify both ends of the same cable. You can connect the component that creates the tone to one end of the wire in the office. Next, you go to the wiring closet and begin touching the speaker probe to different wires. When you hear the tone, you have found the wire.

Cable tester

Cable testers are used to verify that a cable is wired correctly and is operational. Many include LED displays to show exactly how the cable is wired. If the cable is wired incorrectly, the cable tester shows specifically which pins have the wrong wires.

True or false? A cable tester is used to trace cables going between two floors of a building.

Answer: False. The cable tester is used to test the operation of a cable but doesn’t include the capabilities of a toner probe to trace cables.

Cable testers are often used with twisted-pair cables. They have RJ-45 ports where you connect the cable. The cable tester first verifies the wiring and then verifies that the cable meets operational characteristics. For example, a cable tester can verify that a CAT 6 cable can transmit data at a rate of 10 Gbps using a frequency of 250 MHz.

Loopback plug

A loopback plug is a simple plug that loops transmit signals back into the receive signals. A simple loopback plug is an RJ-45 plug with send pins connected to the transmit pins.

True or false? A loopback plug is used to test the characteristics of a cable.

Answer: False. A loopback plug is used to check a NIC. Cable testers are used to check characteristics of a cable.

Punchdown tool

A punchdown tool is used to attach twisted-pair cables to wall jacks or punchdown blocks in wiring closets. The tool has a spring that punches down on a wire when pressed. The technician places the wire in the correct location on the wall jack or punchdown block and presses down with the punchdown tool. When the spring releases, it pushes the wire into the connector.

True or false? You must remove the jacket covering before securing a wire with a punchdown tool.

Answer: False. The jacket covering and insulation of a wire is removed when the punchdown tool forces the wire into place.

There are normally several individual segments between a computer in an office and a switch in a wiring closet, as follows:

  • One cable runs from the computer to the wall jack. It has RJ-45 connectors on each end, and a crimper is used to secure the RJ-45 connectors onto the cable.

  • Another cable runs between the wall jack and the wiring closet. This cable runs through walls, ceilings, and/or plenum spaces. It is connected to the wall jack on one end and to the back of a punchdown block on the other end. The punchdown tool secures the wire to the wall jack and the punchdown block.

  • The last segment is a short patch cable that runs from the front of the punchdown block to a port on a hub or a switch. The devices are mounted in a bay close to each other. RJ-45 connectors are attached both ends of the patch cable with a crimper.

Can you answer these questions?

You can find the answers to these questions at the end of this chapter.

  1. What type of tool is used to connect RJ-45 connectors to twisted-pair cable?

  2. What type of tool is used to trace wires between two rooms?

  3. What computer component is a loopback plug commonly used to test?

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