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ETA · Last updated November 2026

ETA Fiber Optics Technician, Outside Plant (FOT-OSP): free practice test

FOT-OSP is ETA's technician-level certification for outside plant single-mode fiber: G.652, G.655 and G.657 fibers, OSP cable, fusion and mechanical splicing, PON/FTTx hardware, loss budgets and OTDR testing. The 75-question, 2-hour knowledge exam needs 75% and follows ETA's 15-category competency list, including NESC, NEC and field safety. A hands-on course and skills exam at an ETA-approved school are also required; this prep covers only the written exam.

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About the ETA FOT-OSP exam

FOT-OSP is ETA's technician-level certification for outside plant single-mode fiber: G.652, G.655 and G.657 fibers, OSP cable, fusion and mechanical splicing, PON/FTTx hardware, loss budgets and OTDR testing. The 75-question, 2-hour knowledge exam needs 75% and follows ETA's 15-category competency list, including NESC, NEC and field safety. A hands-on course and skills exam at an ETA-approved school are also required; this prep covers only the written exam.

What's on the exam

ETA FOT-OSP
Light, Single-Mode Fiber and Dispersion
7 key facts
OSP Cables and Cable Installation
7 key facts
Active Devices and Connectors
7 key facts
Passive Components, PON and FTTx
7 key facts
Splicing, Closures and OSP Hardware
7 key facts
Link Budgets and Power Measurement
7 key facts
OTDR and Acceptance Testing
8 key facts
OSP Safety
7 key facts

Each branch is a topic in the official outline. Members see every key fact on the full mind map. Read the free study guide →

How to pass the ETA FOT-OSP exam

  • The FOT-OSP competency list is single-mode only and PON-heavy. Know the GPON and XGS-PON wavelengths, splitter losses (1:2 to 1:32) and the role of the OLT, FDH, FAT, MST and ONT.
  • Bring a scientific calculator for dBm and splitter math. Measured splitter loss is input dBm minus output dBm; compare it with 10 log N.
  • OTDR questions dominate the testing categories: bidirectional averaging, dual-wavelength bend checks, ghosts, dead zones and pulse width trade-offs. Learn what each signature looks like.
  • Safety and codes are their own category: laser classes, SDS, confined spaces, NESC for aerial and buried plant, NEC rules where cable enters a building.

Save your results and get your Readiness Score

Create a free account after the test: your score by topic, a mistakes bank, the complete study notes for the first topic, flashcards and the RCDD Numbers & Formulas Sheet.

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What's in the premium ETA FOT-OSP prep

Premium ETA FOT-OSP prep is studied one topic at a time. Each step starts with that topic's key notes and flashcard deck, then its own question sets of 25, so you master one topic before you move to the next. When every topic is strong, the 6 full mock exams show you're ready.

3,000practice questions, every answer explained
6full-length mock exams, 75 questions each, timed
800flashcards with spaced repetition, sorted by topic
60comprehensive key notes across 8 topics

Your step-by-step study path

  1. 1
    Light, Single-Mode Fiber and Dispersion8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Notes free with an account
  2. 2
    OSP Cables and Cable Installation8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  3. 3
    Active Devices and Connectors8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  4. 4
    Passive Components, PON and FTTx8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  5. 5
    Splicing, Closures and OSP Hardware7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  6. 6
    Link Budgets and Power Measurement7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  7. 7
    OTDR and Acceptance Testing7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  8. 8
    OSP Safety7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  9. Final step: 6 full mock exams75 questions each, timed like test day. Pass them, then book your exam.
    Premium
Free with an account

Read the complete ETA FOT-OSP study notes for “Light, Single-Mode Fiber and Dispersion”

Our first full set of comprehensive notes, about 14 minutes of reading: ITU-T single-mode fiber types · Dispersion and attenuation · Wavelengths, bands and WDM · Decibels and OSP vocabulary, a worked exam example, the traps examiners use and a one-minute recap. Create a free account to read it and see how premium notes work before you decide.

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Study tools included

3,000 practice questions

3,000 exam-style questions per exam, organized topic by topic in sets of 25. Every answer explained, with the rule it comes from.

6 full mock exams

6 full-length timed mock exams per exam, with real question counts and time limits, so test day feels like practice day.

Exam Readiness Score

One 0 to 100 number that tells you when you're ready to book. Reach 80 and you're covered by our Pass Guarantee.

800 flashcards + spaced repetition

800 flashcards per exam, in a deck for each topic, that come back right before you'd forget them. Five minutes a day keeps every number fresh.

60 comprehensive key notes

60 key notes per exam, split across its topics and each explained in full: the concepts, worked exam examples, the traps examiners use and a quick recap. Your first set is free with an account.

Mind maps

See the whole exam on one screen: every topic and the facts under it.

Sample questions with answers

These are the questions in the free test above, with answers. Try the test first. You'll learn more by getting some wrong.

1. A long-haul route will carry many closely spaced DWDM channels in the C-band. Which ITU-T fiber type is designed to keep some dispersion at 1550 nm so four-wave mixing between channels is suppressed?
Answer: G.655. G.655 non-zero dispersion-shifted fiber keeps a small, controlled dispersion in the C-band, which prevents the phase matching that drives four-wave mixing. G.653 shifts zero dispersion right onto 1550 nm, which makes four-wave mixing worse. G.652.D is standard low water peak fiber and G.657 is bend-insensitive.
2. A transmitter launches 2 mW into a fiber span, and the receiver measures 50 µW. What is the span loss?
Answer: 16 dB. Convert both to dBm: 2 mW is 10 log 2 = +3.0 dBm, and 50 µW (0.05 mW) is 10 log 0.05 = −13.0 dBm. Loss is +3.0 − (−13.0) = 16 dB. 40 is the linear power ratio, not decibels, and 13 dB forgets the transmitter's +3 dBm.
3. Sheath markings on a stranded loose tube cable read 3,412 ft at one end and 8,957 ft at the other. Measured from the end of the launch cable, with the IOR set from the cable data sheet, the OTDR shows the fiber end at 5,610 ft. What is the most likely explanation?
Answer: Normal helical lay makes the fiber longer than the sheath. The sheath length is 8,957 − 3,412 = 5,545 ft, and the fiber reads 65 ft (about 1.2%) longer. Fibers in stranded loose tubes spiral around the central member, so fiber length normally exceeds sheath length by around 1 to 2%. Meter markings would make the sheath far longer than the fiber reading.
4. An outside plant cable with an outside diameter of 0.6 in is being pulled at its rated tension through a duct bank. Under TIA-568.3, what minimum bend radius applies during the pull?
Answer: 12 in. Outside plant cable needs 20 times its outside diameter under tensile load and 10 times with no load: 20 × 0.6 in = 12 in. 6 in is the installed (no-load) radius, and 9 in uses the 15 times inside plant figure. Pulleys and capstans must have a diameter of at least twice that radius.
5. An FTTH drop ends in a green SC connector. A technician's spare jumper has blue SC connectors. What happens if the two are mated in an adapter?
Answer: High loss and reflectance, with endface damage risk. Green means APC (an 8° angled endface) and blue means UPC (flat). Mating them leaves an angled air gap, so loss and reflectance rise sharply and the endfaces can be chipped. Always mate APC to APC; in PON systems the RF video overlay is especially sensitive to reflection.
6. A 1550 nm DWDM channel needs a source with a very narrow spectral width and a single longitudinal mode. Which source is used?
Answer: Distributed feedback laser. A DFB laser has a grating along its cavity that selects one longitudinal mode, giving a very narrow linewidth that fits tight DWDM spacing and limits chromatic dispersion. A Fabry-Perot laser emits several modes over a few nanometers. LEDs and 850 nm VCSELs are multimode sources.
7. With a 1490 nm source, a technician measures −1.0 dBm at the input of a 1:32 splitter and −18.5 dBm at one output port. How does the measured loss compare with theory?
Answer: 17.5 dB, about 2.4 dB above the theoretical 15.1 dB. Measured loss is input minus output: −1.0 − (−18.5) = 17.5 dB. The ideal 1:32 split is 10 log 32 = 15.1 dB, so the port shows about 2.4 dB of excess and non-uniformity loss, a normal range for a real splitter. Using the output reading alone as the loss is the common error.
8. In a GPON system, which wavelength carries the upstream signal from the ONT to the OLT?
Answer: 1310 nm. GPON (ITU-T G.984) sends data downstream at 1490 nm and upstream at 1310 nm, with 1550 nm reserved for an RF video overlay. XGS-PON moves to 1577 nm downstream and 1270 nm upstream so it can coexist on the same fiber. 1625 nm is used for in-service OTDR monitoring.
9. Twelve fibers in one buffer tube of a 144-fiber cable must be spliced to a new distribution cable at a closure, while the other fibers stay in service. Which method is used?
Answer: Mid-entry: open the sheath and cut only the 12 fibers. A mid-entry (mid-span access) removes a window of sheath, lets the untouched tubes and fibers pass through the closure uncut, and opens only the tube whose fibers are needed. Cutting the whole cable takes every customer out of service. A splitter would share one fiber's signal, not provide 12 new fibers.
10. A fusion splicer estimates 0.45 dB loss on a single-mode splice, and its image shows a 2.5° cleave angle on one fiber. What should the technician do?
Answer: Break the splice, recleave and resplice. A cleave angle that large is an extrinsic fault that causes high loss and weak splices; most splicers reject cleaves over about 1°. Break it out, clean, recleave and resplice. Re-arcing cannot fix a bad end angle, and the protection sleeve has no effect on optical loss.
11. A 12 km single-mode OSP span has a connector pair at each end and 5 fusion splices. Using 0.5 dB/km, 0.75 dB per mated pair and 0.3 dB per splice, what is the not-to-exceed loss?
Answer: 9.00 dB. Fiber: 12 × 0.5 = 6.00 dB. Connectors: 2 × 0.75 = 1.50 dB. Splices: 5 × 0.3 = 1.50 dB. Total 9.00 dB. Leaving out the connectors gives 7.50 dB, and counting only one end gives 8.25 dB. Measured loss above the not-to-exceed figure means the span needs troubleshooting.
12. At a splice closure, a technician must find which of 96 live fibers is the one being tested from the central office, without breaking any fiber. What is the usual method?
Answer: Send a 2 kHz modulated tone and detect it with a clip-on fiber identifier. A light source modulated at 2 kHz puts a tone on the fiber. A fiber identifier clamps a small macrobend onto the buffered fiber, picks up the leaked light and shows the tone and traffic direction without interrupting service. A visual fault locator's red light fades out within a few kilometers, so it cannot cross a long span.
13. An OTDR shows an event at a splice closure measuring 0.10 dB at 1310 nm and 0.85 dB at 1550 nm. What is the most likely cause?
Answer: A tight bend in the splice tray. Bend loss rises steeply with wavelength, so a much larger loss at 1550 nm than at 1310 nm points to a macrobend, often fiber coiled too tightly in a tray. A bad cleave or a splice defect gives similar loss at both wavelengths. That is why OSP acceptance testing uses two wavelengths.
14. An OTDR trace of a 4.2 km span shows a highly reflective connector at 1.1 km and a small reflective spike at exactly 2.2 km, with no loss across the spike. What is the spike?
Answer: A ghost echo of the reflection at 1.1 km. A ghost is an echo of a strong reflection that bounces back and forth, so it appears at a multiple of the real event's distance and shows no loss. A mechanical splice or partial break would cause a loss step. Cleaning or improving the strong reflection, or changing the range and pulse settings, confirms it.
15. A crew must enter an underground vault to splice cable. Under OSHA confined space practice, what must happen before anyone enters?
Answer: Test the air for oxygen and flammable and toxic gases. Vaults and manholes can hold too little oxygen or hold flammable or toxic gases that you cannot see or smell. Test the atmosphere before entry, ventilate as needed and keep monitoring, with an attendant outside, following the employer's confined space program. Airing it out for a few minutes is not a substitute for testing.

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ETA FOT-OSP exam FAQ

How many questions are on the ETA FOT-OSP exam?

75 questions on the knowledge exam, with a time limit of 2 hours. Format: closed book. eta allows scratch paper and a non-programmable scientific calculator. eta publishes only the question count, not the item types; our practice uses 4-option single-best-answer questions. eta requires a hands-on training course and skills exam from an eta-approved school, so this prep covers only the written knowledge exam.

What is the passing score for ETA FOT-OSP?

75% (about 57 of 75 questions).

How much does the ETA FOT-OSP exam cost?

US$155 exam fee (ETA list price); the hands-on course is priced separately by the school. One free retake within one year of the first attempt. Certification term 4 years, with maintenance required. BICSI fees can change without notice, so confirm on bicsi.org before you apply.

Which languages is the ETA FOT-OSP exam offered in?

English. ETA does not list other language versions for this exam; confirm with ETA or your school.

Where do I take the ETA FOT-OSP exam?

An ETA-approved school with an ETA Course Approval, after the required hands-on course; the exam is proctored by an ETA Certification Administrator, online in ETA's Trapeza system or on paper.

Is this ETA FOT-OSP practice test free?

Yes. The 15-question practice test on this page is free, with an explanation for every answer and no signup. A free account also unlocks the complete study notes for the first topic. The full ETA FOT-OSP prep is Premium at $147 a month for this exam.

What's in the premium ETA FOT-OSP prep?

3,000 practice questions organized topic by topic (Light, Single-Mode Fiber and Dispersion: 375; OSP Cables and Cable Installation: 375; Active Devices and Connectors: 375; Passive Components, PON and FTTx: 375; Splicing, Closures and OSP Hardware: 375; Link Budgets and Power Measurement: 375; OTDR and Acceptance Testing: 375; OSP Safety: 375), 6 full-length timed mock exams of 75 questions, 800 flashcards and 60 comprehensive key notes split across all 8 topics, plus a mistakes bank and the Readiness Score.

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Exam details are summarized from the official candidate information available in October 2026. BICSI changes formats and fees, so confirm with ETA International (Electronics Technicians Association); certification programs accredited by ICAC to ISO/IEC 17024 before you book. RCDDQuizBank is not affiliated with BICSI or Pearson VUE.

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