NCTI Fiber Testing & Maintenance:Frequent Questions With
100% Answers.
1: What is the primary principle behind how an OTDR works?
A) Ohm's Law and conductivity.
B) Rayleigh scattering and Fresnel reflection.
C) Direct power measurement.
D) Wavelength division multiplexing.
correct answer: B
2: What happens to the OTDR's performance when you increase the pulse width?
A) Resolution increases but distance decreases.
B) The dynamic range increases, but the ability to distinguish close events decreases.
C) The dead zone is eliminated.
D) Only the color of the trace changes.
correct answer: B
3: When the distance on an OTDR trace doesn't match the cable's physical markings, what should be
adjusted?
A) Laser power.
B) Pulse width.
C) Index of Refraction (IOR) settings.
D) Averaging time.
correct answer: C
4: What is the purpose of using a "Launch Fiber" or "Dead Zone Box" with an OTDR?
A) To amplify the signal.
B) To allow the OTDR to recover from the initial reflection and measure the first connector.
C) To protect the technician's eyes.
D) To convert single-mode light to multimode.
correct answer: B
5: According to industry standards, how long should a launch fiber be?
A) 1 meter.
B) Exactly the same length as the span under test.
C) At least 20 times the length of the OTDR's shortest pulse width.
D) No longer than 10 meters.
correct answer: C
6: What is the difference between Reflectance and Optical Return Loss (ORL)?
A) There is no difference.
B) Reflectance measures a single component; ORL measures the sum of all components in a link.
C) Reflectance is for splices; ORL is for connectors.
D) ORL is only measured on multimode fiber.
correct answer: B
7: What is the most common cause of a "Gainer" on an OTDR trace?
A) A perfect fusion splice.
B) A mismatch in Mode Field Diameter (MFD) between two fibers.
C) A faulty laser in the OTDR.
, D) High moisture levels in the splice tray.
correct answer: B
8: How do you determine the true loss of a splice that shows a "Gainer"?
A) Subtract 0.5 dB from the reading.
B) Average the results of a bidirectional test.
C) Ignore the reading; it is a ghost reflection.
D) Multiply the gain by two.
correct answer: B
9: Which OTDR setting must always exceed the total length of the fiber span being tested?
A) Pulse width.
B) Threshold.
C) Range.
D) Resolution.
correct answer: C
10: What does a non-reflective "step down" on an OTDR trace typically indicate?
A) A mechanical connector.
B) A fusion splice or a macrobend.
C) The end of the fiber.
D) A laser failure.
correct answer: B
11: What topology do most FTTx (Fiber-to-the-x) networks use?
A) Ring.
B) Mesh.
C) Point-to-Multipoint (P2MP).
D) Star-Bus.
correct answer: C
12: Improper use of nylon tie wraps on fiber bundles can induce which problem?
A) Fiber rot.
B) Microbends.
C) Static interference.
D) Laser bleaching.
correct answer: B
13: What is the result of damage to a fiber cable's outer jacket during installation?
A) Increased bandwidth.
B) Moisture migration into the cable.
C) Change in fiber color.
D) Spontaneous fusion of fibers.
correct answer: B
14: In a proactive maintenance plan, what is the technician's primary goal?
A) Only fixing broken cables.
B) Cleaning every connector every day.
C) Recognizing, locating, and remedying potential problems before they cause failures.
D) Documenting the names of all customers on a node.
correct answer: C
100% Answers.
1: What is the primary principle behind how an OTDR works?
A) Ohm's Law and conductivity.
B) Rayleigh scattering and Fresnel reflection.
C) Direct power measurement.
D) Wavelength division multiplexing.
correct answer: B
2: What happens to the OTDR's performance when you increase the pulse width?
A) Resolution increases but distance decreases.
B) The dynamic range increases, but the ability to distinguish close events decreases.
C) The dead zone is eliminated.
D) Only the color of the trace changes.
correct answer: B
3: When the distance on an OTDR trace doesn't match the cable's physical markings, what should be
adjusted?
A) Laser power.
B) Pulse width.
C) Index of Refraction (IOR) settings.
D) Averaging time.
correct answer: C
4: What is the purpose of using a "Launch Fiber" or "Dead Zone Box" with an OTDR?
A) To amplify the signal.
B) To allow the OTDR to recover from the initial reflection and measure the first connector.
C) To protect the technician's eyes.
D) To convert single-mode light to multimode.
correct answer: B
5: According to industry standards, how long should a launch fiber be?
A) 1 meter.
B) Exactly the same length as the span under test.
C) At least 20 times the length of the OTDR's shortest pulse width.
D) No longer than 10 meters.
correct answer: C
6: What is the difference between Reflectance and Optical Return Loss (ORL)?
A) There is no difference.
B) Reflectance measures a single component; ORL measures the sum of all components in a link.
C) Reflectance is for splices; ORL is for connectors.
D) ORL is only measured on multimode fiber.
correct answer: B
7: What is the most common cause of a "Gainer" on an OTDR trace?
A) A perfect fusion splice.
B) A mismatch in Mode Field Diameter (MFD) between two fibers.
C) A faulty laser in the OTDR.
, D) High moisture levels in the splice tray.
correct answer: B
8: How do you determine the true loss of a splice that shows a "Gainer"?
A) Subtract 0.5 dB from the reading.
B) Average the results of a bidirectional test.
C) Ignore the reading; it is a ghost reflection.
D) Multiply the gain by two.
correct answer: B
9: Which OTDR setting must always exceed the total length of the fiber span being tested?
A) Pulse width.
B) Threshold.
C) Range.
D) Resolution.
correct answer: C
10: What does a non-reflective "step down" on an OTDR trace typically indicate?
A) A mechanical connector.
B) A fusion splice or a macrobend.
C) The end of the fiber.
D) A laser failure.
correct answer: B
11: What topology do most FTTx (Fiber-to-the-x) networks use?
A) Ring.
B) Mesh.
C) Point-to-Multipoint (P2MP).
D) Star-Bus.
correct answer: C
12: Improper use of nylon tie wraps on fiber bundles can induce which problem?
A) Fiber rot.
B) Microbends.
C) Static interference.
D) Laser bleaching.
correct answer: B
13: What is the result of damage to a fiber cable's outer jacket during installation?
A) Increased bandwidth.
B) Moisture migration into the cable.
C) Change in fiber color.
D) Spontaneous fusion of fibers.
correct answer: B
14: In a proactive maintenance plan, what is the technician's primary goal?
A) Only fixing broken cables.
B) Cleaning every connector every day.
C) Recognizing, locating, and remedying potential problems before they cause failures.
D) Documenting the names of all customers on a node.
correct answer: C
