Troubleshooting Physical Networks

Question 1

Troubleshooting Methodology

Answer 1

1. Identify the problem
2. Establish a theory to determine the cause
3. Test the theory to determine the cause
4. Establish a plan of action to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary
6. Verify the whole system functionality and if applicable, implement preventive
   measures
7. Document findings, actions, outcomes, and lesson learned

Question 2

Riser Cable

Answer 2

Used to run network cables vertically between floors in a building in a
cable riser or elevator shaft

Riser cables cannot be used in plenum spaces since they are not made
from PVC or FEP

Question 3

Rollover/Console Cable

Answer 3

A type of null-modem cable that is used to connect a computer terminal to a router’s console port

Question 4

Wire Map Tool

Answer 4

Like a cable tester, but it works specifically for twisted pair ethernet cables

Question 5

Wire Map: Open Pair

Answer 5

Occurs when one or more of the conductors in the pair are not connected to a pin at one or the other end

Question 6

Wire Map: Short Pair

Answer 6

Occurs when the conductors of a wire pair are connected to each other at any location in the cable

Question 7

Wire Map: Short Between Pairs

Answer 7

Occurs when the conductors of two wires in different pairs are connected at any location in the cable

Question 8

Wire Map: Reversed Pair

Answer 8

Occurs when the two wires in a single pair are connected to the opposite pins of the pair at the other end of the cable

Question 9

Wire Map: Crossed Pairs

Answer 9

Occur when both wires of one color pair are connected to the pins of a different color pair at the opposite end

Question 10

Wire Map: Split Pairs

Answer 10

Occur when the wire from one pair is split away from the other and crosses over a wire in an adjacent pair

Question 11

Multimeter

Answer 11

Checks the voltage or the amperage or the resistance of a copper cable

Used to verify if a cable is broken or not

Used to check coaxial cables to ensure there is no cuts or breaks in the
middle of a patch cable, or test power sources or power cords

Question 12

TDR

Answer 12

Time-Domain Reflectometer:
Locate breaks in a copper cable and provide an estimate of the severity
and the distance to the break

OTDR (Optical): Used for fiber optic cables

Question 13

Fiber Light Meter

Answer 13

A device that provides a continuous wave of stable source of energy for
attenuation measurements

Question 14

Fusion Splicer

Answer 14

A machine that is used to permanently join two fibers together

Question 15

Tap

Answer 15

A simple device that connects directly to the cabling infrastructure to split or copy packets for use in analysis, security, or general network management

Question 16

Cable Signal Issues: Attenuation

Answer 16

Loss of signal strength on a network cable or connection over the length of the cable

Higher frequency = higher bandwidth

Question 17

Cable Signal Issues: Attenuation - Noise

Answer 17

Additional electrical or radio frequency noise in the areas where your network cables are operating

Use an amplifier/repeater if necessary

Question 18

Cable Signal Issues: dB Loss

Answer 18

Measures the amount of signal deterioration we are experiencing on a given connection

Question 19

Copper Cable Issues: Incorrect Pinouts

Answer 19

By default, the patch panel should use the TIA-568B pinout

OW, O, GW, B, BW, G, BrW, Br

Question 20

Copper Cable Issues: Bad Port

Answer 20

If you suspect a bad port on a switch or router, you should connect a loopback plug to the port on that device and run a test using specialized software

Question 21

Copper Cable Issues: Open

Answer 21

There is nothing on the other end of the connection or there’s a break in the wires between the source and the destination

Question 22

Copper Cable Issues: Short

Answer 22

Indicates there are two wires are connected together somewhere in the connection

Question 23

Fiber Cable Issues: Transceiver

Answer 23

A transmitter and a receiver combined into a single device that converts a
network connection from one type to another

They are designed to support a certain type of connection and a certain
cable type

Question 24

Fiber Cable Issues: Dry Cleaning

Answer 24

Using light pressure while rubbing the end face of a fiber cable or connector with a dry-cleaning cloth in one direction

Question 25

Fiber Cable Issues: Wet Cleaning

Answer 25

Moistening a piece of lint-free cloth with a fiber optic cleaning solution and wiping the end face of the cable or connector

Question 26

Ethernet Issues: Duplex Mismatch

Answer 26

When one device thinks the connection is full duplex and the other thinks it is half duplex

Ensure both devices are configured to auto negotiate the connection properly