NCTI Fiber Testing & Maintenance: 100 Exam Questions With
Correct Answers Version 2026/2027.
1:Analyzing OTDR Trace Anomalies and Mode Field Diameter Mismatch
A technician is performing a maintenance sweep on a long-haul fiber link. The OTDR trace shows a
"gainer" at a fusion splice located 20km from the source. This occurs when the fiber being joined has
a larger Mode Field Diameter (MFD) than the fiber it is spliced into. What is the standard NCTI
procedure for determining the actual loss?
A) Accept the gainer as a perfect 0.00 dB splice.
B) Perform a bidirectional test and average the two readings to find the true loss.
C) Decrease the OTDR pulse width to 10ns.
D) Re-splice the fiber immediately.
Correct Answer: B
2: Identifying High-Reflectance Events in High-Bandwidth Systems
During a routine audit, a technician measures the Optical Return Loss (ORL) of a transmitter's output.
The system is experiencing high Bit Error Rates (BER). The OTDR reveals a reflection of -32 dB at the
first patch panel. Why is this a concern?
A) -32 dB is too high; reflections back into the laser cause "relative intensity noise" (RIN).
B) -32 dB is a perfect reading.
C) -32 dB indicates the signal is too strong for the receiver.
D) ORL only applies to analog video signals.
Correct Answer: A
3: Troubleshooting Passive Optical Network (PON) Splitters
A technician is troubleshooting a "Loss of Signal" alarm at an ONT. At the FDH, the technician tests a
1x32 splitter. If the input power is +3.0 dBm and the splitter has a nominal loss of 17.5 dB, what is the
expected power level at the output?
A) -14.5 dBm; use a standard OPM at 1310nm.
B) -20.5 dBm; use a VFL to check for light leaks.
C) -14.5 dBm; use a filtered PON Power Meter to isolate the 1490nm signal.
D) +20.5 dBm; use an OSA to check for wavelength drift.
Correct Answer: C
4: Macro-bend Detection vs. Splice Loss
A fiber link shows a sudden drop in power during a 1550nm test, but the loss is significantly lower
when tested at 1310nm. What does this wavelength-dependent loss difference indicate?
A) A dirty connector at the bulkhead.
B) A macro-bend (physical bend tighter than the minimum radius).
C) Fiber aging or hydrogen darkening.
D) Normal behavior for all fiber types.
Correct Answer: B
5: Safety and Inspection of High-Power Fiber End-Faces
A technician is about to inspect a fiber connector using a video probe. Before inserting the
connector, what is the most critical safety and maintenance step?
A) Look directly at the end-face with the naked eye.
B) Ensure the laser source is disabled to prevent sensor damage or eye injury.
C) Apply a thick layer of Isopropyl Alcohol to the connector.
, D) Wrap the connector in electrical tape.
Correct Answer: B
6: The Role of the Index of Refraction (IOR) in Distance Measurements
If an OTDR IOR setting is configured incorrectly (too high), how will the location of a fault or end-of-
fiber be displayed on the trace?
A) The fault will appear closer than it actually is.
B) The fault will appear further away than it actually is.
C) The fault will not be visible.
D) The signal strength will appear lower.
Correct Answer: B
7: Impact of Improper Cable Dressing on Optical Performance
Tightening nylon tie wraps excessively around a bundle of drop cables induces which specific optical
phenomenon?
A) Chromatic Dispersion.
B) Microbends; loss will be higher at 1550 nm than at 1310 nm.
C) Fresnel Reflection.
D) Modal Noise.
Correct Answer: B
8: Dead Zone Management with Launch Fibers
Why is it necessary to use a "Dead Zone Box" or launch fiber when testing with an OTDR?
A) To amplify the signal.
B) To allow the OTDR to recover from the initial pulse to measure the first connector.
C) To prevent the laser from burning out.
D) To convert the signal from digital to analog.
Correct Answer: B
9: Determining Fiber Directionality with an OFI
Besides detecting the presence of light, what critical information does an Optical Fiber Identifier
(OFI) provide?
A) The data rate.
B) The direction of the signal flow (Traffic Direction).
C) The manufacturer of the cable.
D) The exact distance to the headend.
Correct Answer: B
10: Maintenance Standards for Core Zone Pits
If a technician finds several pits located specifically in the Core Zone of a connector during
inspection, what is the required action?
A) Use a "one-click" cleaner.
B) Ignore the pits if the Adhesive Zone is clean.
C) Replace or re-terminate the connector; pits in the core cause permanent scattering.
D) Apply index-matching gel.
Correct Answer: C
11: Optical Loss Test Set (OLTS) Referencing
When using an OLTS to measure attenuation, what is the "One Jumper" method used for?
A) To test the battery of the light source.
Correct Answers Version 2026/2027.
1:Analyzing OTDR Trace Anomalies and Mode Field Diameter Mismatch
A technician is performing a maintenance sweep on a long-haul fiber link. The OTDR trace shows a
"gainer" at a fusion splice located 20km from the source. This occurs when the fiber being joined has
a larger Mode Field Diameter (MFD) than the fiber it is spliced into. What is the standard NCTI
procedure for determining the actual loss?
A) Accept the gainer as a perfect 0.00 dB splice.
B) Perform a bidirectional test and average the two readings to find the true loss.
C) Decrease the OTDR pulse width to 10ns.
D) Re-splice the fiber immediately.
Correct Answer: B
2: Identifying High-Reflectance Events in High-Bandwidth Systems
During a routine audit, a technician measures the Optical Return Loss (ORL) of a transmitter's output.
The system is experiencing high Bit Error Rates (BER). The OTDR reveals a reflection of -32 dB at the
first patch panel. Why is this a concern?
A) -32 dB is too high; reflections back into the laser cause "relative intensity noise" (RIN).
B) -32 dB is a perfect reading.
C) -32 dB indicates the signal is too strong for the receiver.
D) ORL only applies to analog video signals.
Correct Answer: A
3: Troubleshooting Passive Optical Network (PON) Splitters
A technician is troubleshooting a "Loss of Signal" alarm at an ONT. At the FDH, the technician tests a
1x32 splitter. If the input power is +3.0 dBm and the splitter has a nominal loss of 17.5 dB, what is the
expected power level at the output?
A) -14.5 dBm; use a standard OPM at 1310nm.
B) -20.5 dBm; use a VFL to check for light leaks.
C) -14.5 dBm; use a filtered PON Power Meter to isolate the 1490nm signal.
D) +20.5 dBm; use an OSA to check for wavelength drift.
Correct Answer: C
4: Macro-bend Detection vs. Splice Loss
A fiber link shows a sudden drop in power during a 1550nm test, but the loss is significantly lower
when tested at 1310nm. What does this wavelength-dependent loss difference indicate?
A) A dirty connector at the bulkhead.
B) A macro-bend (physical bend tighter than the minimum radius).
C) Fiber aging or hydrogen darkening.
D) Normal behavior for all fiber types.
Correct Answer: B
5: Safety and Inspection of High-Power Fiber End-Faces
A technician is about to inspect a fiber connector using a video probe. Before inserting the
connector, what is the most critical safety and maintenance step?
A) Look directly at the end-face with the naked eye.
B) Ensure the laser source is disabled to prevent sensor damage or eye injury.
C) Apply a thick layer of Isopropyl Alcohol to the connector.
, D) Wrap the connector in electrical tape.
Correct Answer: B
6: The Role of the Index of Refraction (IOR) in Distance Measurements
If an OTDR IOR setting is configured incorrectly (too high), how will the location of a fault or end-of-
fiber be displayed on the trace?
A) The fault will appear closer than it actually is.
B) The fault will appear further away than it actually is.
C) The fault will not be visible.
D) The signal strength will appear lower.
Correct Answer: B
7: Impact of Improper Cable Dressing on Optical Performance
Tightening nylon tie wraps excessively around a bundle of drop cables induces which specific optical
phenomenon?
A) Chromatic Dispersion.
B) Microbends; loss will be higher at 1550 nm than at 1310 nm.
C) Fresnel Reflection.
D) Modal Noise.
Correct Answer: B
8: Dead Zone Management with Launch Fibers
Why is it necessary to use a "Dead Zone Box" or launch fiber when testing with an OTDR?
A) To amplify the signal.
B) To allow the OTDR to recover from the initial pulse to measure the first connector.
C) To prevent the laser from burning out.
D) To convert the signal from digital to analog.
Correct Answer: B
9: Determining Fiber Directionality with an OFI
Besides detecting the presence of light, what critical information does an Optical Fiber Identifier
(OFI) provide?
A) The data rate.
B) The direction of the signal flow (Traffic Direction).
C) The manufacturer of the cable.
D) The exact distance to the headend.
Correct Answer: B
10: Maintenance Standards for Core Zone Pits
If a technician finds several pits located specifically in the Core Zone of a connector during
inspection, what is the required action?
A) Use a "one-click" cleaner.
B) Ignore the pits if the Adhesive Zone is clean.
C) Replace or re-terminate the connector; pits in the core cause permanent scattering.
D) Apply index-matching gel.
Correct Answer: C
11: Optical Loss Test Set (OLTS) Referencing
When using an OLTS to measure attenuation, what is the "One Jumper" method used for?
A) To test the battery of the light source.
