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ETA · Last updated November 2026

ETA Fiber Optics Installer for Data Centers (FIDC): free practice test

FIDC covers installing, terminating, splicing, testing and troubleshooting fiber and copper cabling in data centers, enterprise networks and LANs, aligned with TIA, NEC, ISO/IEC, ITU and IEEE standards. The written exam has 75 questions in 2 hours with a 75% pass mark, across 16 competency areas from light theory and MPO polarity to IEEE 802.3 link budgets and Uptime Institute tiers. A hands-on course comes first; this prep covers only the written exam.

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About the ETA FIDC exam

FIDC covers installing, terminating, splicing, testing and troubleshooting fiber and copper cabling in data centers, enterprise networks and LANs, aligned with TIA, NEC, ISO/IEC, ITU and IEEE standards. The written exam has 75 questions in 2 hours with a 75% pass mark, across 16 competency areas from light theory and MPO polarity to IEEE 802.3 link budgets and Uptime Institute tiers. A hands-on course comes first; this prep covers only the written exam.

What's on the exam

ETA FIDC
Light, Transmission and Safety
8 key facts
Fiber Construction, Types and Characteristics
8 key facts
Fiber and Copper Cabling and NEC Listings
8 key facts
Splicing, Connectors and MPO Polarity
8 key facts
Sources, Receivers, Passives and POLAN
8 key facts
Cable Installation and Data Center Hardware
8 key facts
Link Budgets, Data Center Links and Tiers
8 key facts
Testing, Troubleshooting and Documentation
8 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 FIDC exam

  • The FIDC list names exact references: ANSI/TIA-568.3-D for components and MPO polarity, TIA-942 for data centers, IEEE 802.3 clauses 86 and 95 for 40G and 100G links, and TIA-526-14 for multimode loss. Know what each covers.
  • Data center link questions turn on reach: 100GBASE-SR4 runs 70 m on OM3 and 100 m on OM4. Learn the reach and fiber counts of the common short-reach Ethernet variants.
  • Expect MPO polarity: Type A adapters mate key-up to key-down, Type B key-up to key-up, and Type B flips fiber 1 to position 12.
  • 75 questions in 2 hours is 96 seconds each. Bring a non-programmable calculator for power budgets, NA and not-to-exceed loss, and answer every question.

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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 FIDC prep

Premium ETA FIDC 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, Transmission and Safety8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Notes free with an account
  2. 2
    Fiber Construction, Types and Characteristics8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
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  3. 3
    Fiber and Copper Cabling and NEC Listings8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  4. 4
    Splicing, Connectors and MPO Polarity8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  5. 5
    Sources, Receivers, Passives and POLAN7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  6. 6
    Cable Installation and Data Center Hardware7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  7. 7
    Link Budgets, Data Center Links and Tiers7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  8. 8
    Testing, Troubleshooting and Documentation7 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 FIDC study notes for “Light, Transmission and Safety”

Our first full set of comprehensive notes, about 14 minutes of reading: Light and the index of refraction · Total internal reflection and Fresnel reflection · Links, multiplexing, dB and dBm · Safety, 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. For a low-latency link between two data halls, a designer needs the one-way delay per kilometer of single-mode fiber with a group index of 1.468. What is it?
Answer: About 4.9 µs per km. Light in the fiber travels at c/n = 299,792 / 1.468, about 204,000 km/s, so 1 km takes about 4.9 µs. 3.3 µs is the delay in a vacuum, 2.3 µs comes from multiplying by the index instead of dividing, and 9.8 µs is a round trip. Shorter fiber routes are the main way to cut latency.
2. A multimode fiber has a numerical aperture of 0.200. What is the full acceptance cone angle?
Answer: About 23 degrees. The acceptance half-angle is arcsin(NA) = arcsin(0.200), about 11.5 degrees, so the full cone is about 23 degrees. Light entering outside the cone is not guided by total internal reflection and leaks into the cladding. Mixing up the half-angle and the full cone is the usual trap.
3. An OTDR shows a single-mode fiber at 0.33 dB/km at 1310 nm and 0.19 dB/km at 1550 nm. A trainee thinks the tester is faulty. What explains the difference?
Answer: Rayleigh scattering falls steeply as wavelength rises. Rayleigh scattering, the main intrinsic loss in silica, falls with the fourth power of wavelength, so 1550 nm has lower loss than 1310 nm. Zero dispersion in standard fiber is near 1310 nm, not 1550 nm, and the water peak is near 1383 nm. Dispersion spreads pulses but does not cause loss.
4. A cable for remote devices has optical fibers and current-carrying copper conductors under one jacket. How does the NEC classify it?
Answer: Composite optical fiber cable. The NEC defines a composite optical fiber cable as one containing optical fibers and current-carrying electrical conductors. Conductive optical fiber cable has metal that does not carry current, such as armor or a metallic strength member. Hybrid is a TIA term for different cable units under one sheath, not an NEC category.
5. During a data center refresh, old fiber cables above a suspended ceiling are no longer terminated at either end and are not tagged for future use. What does NEC Article 770 require?
Answer: Remove the accessible portions of the abandoned cable. Article 770 requires the accessible portion of abandoned optical fiber cable to be removed, because unused cable adds fuel and smoke load. Cable can stay only if it is tagged as reserved for future use. Fiber jackets burn even though the fibers carry no current.
6. A Type-B MPO adapter mates two 12-fiber connectors key-up to key-up. The fiber in position 1 of one connector meets which position on the other?
Answer: Position 12. Mating key-up to key-up flips the array, so position 1 meets position 12, 2 meets 11 and so on. Type-A adapters mate key-up to key-down, so position 1 meets position 1. Mixing adapter types in one channel is a common reason a parallel optic link fails polarity.
7. A UPC connector passes visual inspection, but mated pairs show high insertion loss and reflectance. Interferometry shows an apex offset beyond the Telcordia GR-326 limit. What is the problem?
Answer: The polish dome is off-center, so the cores may not touch. Apex offset is the distance between the polish dome's high point and the fiber core. Too much offset means the fiber cores may not make physical contact, leaving a gap that raises loss and reflectance. GR-326 sets limits on apex offset, radius of curvature and fiber height; visual inspection alone cannot see geometry faults.
8. A crew field-terminates 288 fibers with a no-epoxy, no-polish connector that has a 92% first-pass yield. About how many terminations will need rework?
Answer: 23. An 8% failure rate on 288 terminations is 288 x 0.08 = 23.04, about 23 connectors to redo. 265 is the number that pass, and 29 assumes a 10% failure rate. Low yield costs labor and connectors, which is why data centers often use factory-terminated trunks or fusion splice-on connectors.
9. A 40 km single-mode link at 1550 nm needs a laser source. Why is a DFB laser chosen over a Fabry-Perot laser?
Answer: Its narrow spectral width means less chromatic dispersion. A Fabry-Perot laser emits several longitudinal modes over a few nanometers, while a DFB laser emits one narrow line. Chromatic dispersion grows with spectral width, so DFBs suit long, fast 1550 nm links. VCSELs at 850 nm are the low-cost choice for short multimode links.
10. A long-reach transceiver uses an avalanche photodiode (APD) instead of a PIN photodiode. What is the main reason?
Answer: Its internal gain gives better sensitivity for weak signals. An APD multiplies the photocurrent inside the device, so it can detect weaker signals than a PIN photodiode, which suits long links with high loss. The trade-offs are a high bias voltage, temperature sensitivity and extra noise. PIN photodiodes are simpler and suit short links with power to spare.
11. Each server cabinet has its own access switch, with short patch cords to the servers and fiber uplinks to the aggregation layer. Which TIA-942 arrangement is this?
Answer: Top of rack, with one access switch in each cabinet. Top of rack places an access switch in every cabinet, which keeps server cabling short and moves most horizontal cabling to fiber uplinks, at the cost of more switches to manage. End of row puts the access switches in a cabinet at the end of each row, with longer horizontal runs to each server cabinet.
12. A 95 m OM3 trunk is planned for 100GBASE-SR4. Is this supported under IEEE 802.3?
Answer: No; OM3 is limited to 70 m, while OM4 reaches 100 m. IEEE 802.3 (clause 95) supports 100GBASE-SR4 to 70 m on OM3 and 100 m on OM4, using 8 fibers of a 12-fiber MPO. At 95 m the trunk needs OM4 or OM5 (or a single-mode variant). 150 m is the 40GBASE-SR4 reach on OM4, a common mix-up.
13. A transceiver's minimum launch is -5 dBm and its receiver sensitivity is -15 dBm. The link has 2.0 km of single-mode fiber at 0.4 dB/km, 4 connector pairs at 0.75 dB and 2 splices at 0.3 dB. What is the margin?
Answer: 5.6 dB. The power budget is -5 - (-15) = 10.0 dB. Link loss is 0.8 dB of fiber + 3.0 dB of connectors + 0.6 dB of splices = 4.4 dB, so the margin is 10.0 - 4.4 = 5.6 dB. 4.4 dB is the loss, not the margin, and 10.0 dB is the budget before any loss.
14. Two testers measure the same OM4 link at 850 nm. One uses an overfilled LED launch and reads 0.6 dB more loss. What is the standard way to get repeatable results?
Answer: Use an encircled flux compliant launch for multimode tests. An overfilled launch puts power into high-order modes that are lost in the first connectors, inflating loss. TIA-526-14 and IEC 61280-4-1 use an encircled flux launch condition so different testers agree. Averaging results or changing wavelength does not fix the launch.
15. A damaged 150 m section of indoor single-mode cable is replaced, with a fusion splice at each end. Using TIA-568.3-D maximums of 0.3 dB per splice and 1.0 dB/km for inside plant fiber, what is the not-to-exceed loss for the repair?
Answer: 0.75 dB. Two splices at 0.3 dB is 0.60 dB, and 0.15 km at 1.0 dB/km is 0.15 dB, for 0.75 dB. Using the 0.5 dB/km outside plant figure gives 0.68 dB, and leaving out the fiber gives 0.60 dB. Test the repaired span against this ceiling and record the results.

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ETA FIDC exam FAQ

How many questions are on the ETA FIDC exam?

75 multiple-choice questions, with a time limit of 2 hours. Format: closed book; scratch paper and a non-programmable calculator are allowed. eta requires a hands-on training course from an eta-approved trainer or school, and recommends holding fiber optics technician-inside plant (fot-isp) first. this prep covers only the written knowledge exam.

What is the passing score for ETA FIDC?

75%.

How much does the ETA FIDC exam cost?

US$155 for the exam, with one free retake within one year of the first sitting; course fees are set by the school. Certification term 4 years, with maintenance required. Stand-alone or Journeyman level: holders who later earn the Associate CET (CETa) and have 2+ years of training or experience can upgrade to Journeyman CET for US$55. BICSI fees can change without notice, so confirm on bicsi.org before you apply.

Which languages is the ETA FIDC exam offered in?

English. ETA does not list other languages for FIDC; confirm with ETA or your school.

Where do I take the ETA FIDC exam?

ETA-approved schools and trainers, which run the required hands-on course; the written exam is proctored by an ETA Certification Administrator online (Trapeza) or on paper.

Is this ETA FIDC 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 FIDC prep is Premium at $147 a month for this exam.

What's in the premium ETA FIDC prep?

3,000 practice questions organized topic by topic (Light, Transmission and Safety: 375; Fiber Construction, Types and Characteristics: 375; Fiber and Copper Cabling and NEC Listings: 375; Splicing, Connectors and MPO Polarity: 375; Sources, Receivers, Passives and POLAN: 375; Cable Installation and Data Center Hardware: 375; Link Budgets, Data Center Links and Tiers: 375; Testing, Troubleshooting and Documentation: 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), accredited by ICAC under ISO/IEC 17024 before you book. RCDDQuizBank is not affiliated with BICSI or Pearson VUE.

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