Specialist Testing Exam Practice Test

Fiber Optic Association Certified Fiber Optic Specialist (Testing) Exam Practice Test (CFOS/T) Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the main purpose of fiber optic testing?

a) To increase data transmission speed

b) To verify fiber performance and installation quality

c) To install connectors

d) To clean fiber connectors

Rationale: Testing ensures the fiber optic system meets performance

standards and installation specifications.

• What instrument is primarily used to measure fiber attenuation?

a) OTDR

b) Optical Loss Test Set (OLTS)

c) Optical power meter only

d) Fiber microscope 1 / 4

Rationale: The OLTS measures insertion loss across fiber links to

determine attenuation.

• What is the typical wavelength used for singlemode fiber testing?
• 650 nm
• 850 nm
• 1310 nm and 1550 nm
• 980 nm

Rationale: 1310 nm and 1550 nm are standard wavelengths for

singlemode testing per industry standards.

• What does OTDR stand for?

a) Optical Time Division Receiver

b) Optical Time Domain Reflectometer

c) Optical Transmission Delay Recorder

d) Optical Test Data Reader

Rationale: OTDR stands for Optical Time Domain Reflectometer, used

for analyzing fiber integrity and faults.

5. The main function of an OTDR is to:

a) Measure bandwidth

b) Locate fiber faults and measure distance to events

c) Clean connectors

d) Generate data signals

Rationale: The OTDR measures backscatter and reflections to locate

faults, splices, and connectors. 2 / 4

• What is insertion loss?

a) Gain in fiber

b) Total optical power loss between two test points

c) Power reflected back to source

d) Signal gain after amplification

Rationale: Insertion loss is the total optical power lost through a

connection, splice, or component.

• What unit is used to express optical power?

a) Watts

b) Lumens

• dBm

d) Volts

Rationale: Optical power is typically measured in dBm (decibels

referenced to 1 milliwatt).

• What does a negative dB value represent in fiber testing?

a) Loss of optical power

b) Gain in power

c) Reflection

d) No signal

Rationale: Negative dB indicates a power loss since the output is less

than the input.

• What is the typical loss per connector in a fiber link?
• 0.1 dB 3 / 4

• 0.3–0.5 dB
• 1 dB
• 2 dB

Rationale: Typical connector loss is between 0.3 and 0.5 dB per

mated pair.

• What test method uses a light source and power meter

connected at both ends of the fiber?

a) Reflectance test

b) Insertion loss test

c) OTDR test

d) Polarization test

Rationale: Insertion loss testing requires a light source and power

meter connected to both fiber ends.

• Which of the following affects fiber loss the most?

a) Fiber color code

b) Bending radius

c) Jacket type

d) Connector polish color

Rationale: Excessive bending increases attenuation due to light

escaping from the fiber core.

• What is backscatter in OTDR testing?

a) Signal reflection at connector

b) Scattered light returning to the OTDR from fiber imperfections

• / 4