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ETA · Last updated November 2026

Distributed Antenna Systems (DAS): free practice test

The ETA DAS certification covers installing, maintaining and troubleshooting in-building distributed antenna systems for cellular carriers and public safety, including ERCES and bi-directional amplifiers. The exam has 75 questions in 2 hours with a 75% pass mark and needs no hands-on test. It can be a stand-alone credential or count toward a Journeyman CET with CETa or GCT1.

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About the ETA DAS exam

The ETA DAS certification covers installing, maintaining and troubleshooting in-building distributed antenna systems for cellular carriers and public safety, including ERCES and bi-directional amplifiers. The exam has 75 questions in 2 hours with a 75% pass mark and needs no hands-on test. It can be a stand-alone credential or count toward a Journeyman CET with CETa or GCT1.

What's on the exam

ETA DAS
DAS Fundamentals and Types
7 key facts
Spectrum, Radio Systems and FCC Rules
8 key facts
Safety and RF Exposure
7 key facts
Building Codes and Public Safety Requirements
8 key facts
RF Signal Characteristics, Decibels and Noise
8 key facts
Site Surveys and DAS Equipment
8 key facts
Antennas, Transmission Lines and Passive Components
8 key facts
Installation, Commissioning, Testing and Troubleshooting
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 DAS exam

  • 75 questions in 2 hours is 96 seconds each. Bring a non-programmable calculator and practise dB arithmetic: dBd to dBi, splitter and coupler losses, EIRP and isolation margins.
  • ETA's competency list names specific codes: NFPA 1225 (which replaced NFPA 1221 and 1061), NFPA 72 Chapter 24, IFC Section 510, UL 2524, NEC, NESC, TIA-568 and TIA-606-B. Know what each one controls.
  • Learn the public safety numbers by heart: 95% general and 99% critical-area coverage, -95 dBm and DAQ 3.0, 12-hour battery, isolation 20 dB above gain, NEMA 4 enclosures, 2-hour pathways.
  • FCC rules are a favourite: licensee consent to rebroadcast, Part 90 and section 90.219, Class A versus Class B boosters, and who stays responsible for interference.

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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 DAS prep

Premium ETA DAS 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
    DAS Fundamentals and Types8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Notes free with an account
  2. 2
    Spectrum, Radio Systems and FCC Rules8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  3. 3
    Safety and RF Exposure8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  4. 4
    Building Codes and Public Safety Requirements8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  5. 5
    RF Signal Characteristics, Decibels and Noise7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  6. 6
    Site Surveys and DAS Equipment7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  7. 7
    Antennas, Transmission Lines and Passive Components7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  8. 8
    Installation, Commissioning, Testing and Troubleshooting7 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 DAS study notes for “DAS Fundamentals and Types”

Our first full set of comprehensive notes, about 14 minutes of reading: What a DAS does · Types of DAS · Coverage and the life cycle · SISO and MIMO, 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 20-floor hospital needs multi-carrier LTE and 5G with high capacity, fed from base station equipment in a basement head-end room. Which DAS type fits best?
Answer: An active DAS with a fiber-fed head-end and powered remote units. An active DAS converts the base station signals at a head-end and sends them over fiber to remote units near the antennas, so loss doesn't build up with distance and capacity can come from dedicated base station equipment. Passive coax systems lose too much signal over large, tall buildings, especially at higher frequencies. Consumer boosters aren't designed or permitted for this role.
2. A carrier asks for 2x2 MIMO LTE throughout a new DAS. What does the distribution system need?
Answer: Two independent paths to two antenna elements per location. MIMO gains capacity by sending separate data streams over separate paths, so a 2x2 MIMO DAS needs two independent downlink and uplink paths feeding two antenna elements (spaced antennas or one cross-polarized antenna) at each location. More power or gain on one path is still SISO. Channel filters don't create extra streams.
3. A building owner installs a Class B signal booster to rebroadcast the county's 800 MHz public safety system, without contacting the county. Under FCC rules, what is wrong?
Answer: It needs the county licensee's consent to rebroadcast. Under 47 CFR 90.219, a signal booster for Part 90 services may only be operated with the express consent of the FCC licensee whose frequencies it retransmits, and Class B boosters must also be registered with the FCC. The licensee keeps legal responsibility for its signal and interference, not the building owner. A UL listing and fire permit don't replace licensee consent.
4. A building's public safety DAS must boost one agency's UHF channels, but other licensees operate on nearby UHF frequencies in the same area. Which booster type limits amplification to only the wanted channels?
Answer: A Class A (channelized) signal booster. A Class A booster amplifies only specific, narrow channels, so neighbouring users' frequencies aren't retransmitted or degraded. A Class B booster amplifies a whole band and would pass the other licensees' signals and noise too. Choose Class A where wanted and unwanted channels are close together.
5. A technician must replace a jumper right behind a rooftop donor antenna that is connected to an operating public safety BDA. What is the safe approach?
Answer: Shut down transmit power under a controlled procedure first. RF exposure near transmitting antennas can exceed the maximum permissible exposure limits in FCC OET Bulletin 65 and IEEE C95.1, so the transmitter is shut down or reduced under a controlled procedure first. For an ERCES, the change also triggers fire alarm supervisory signals, so notify the monitoring company and AHJ as required. Gloves don't block RF, and side lobes still radiate.
6. An ERCES design provides a 12-hour battery for the signal boosters. The AHJ has adopted NFPA 1225 (2022) and current IFC Section 510 without amendment, and the building has no standby generator. A reviewer proposes cutting it to 8 hours to save space. What is the right response?
Answer: Keep 12 hours of operation at full capacity, as the codes require. NFPA 1225 and recent IFC editions require ERCES secondary power for at least 12 hours of operation at 100% system capacity; IFC also accepts a 2-hour battery backed by a standby generator, older IFC editions and some local amendments require 24 hours, and the AHJ's adopted edition decides, so check it, but an 8-hour battery doesn't comply here. The manufacturer's data is used to size the battery to the code duration.
7. Grid testing of one floor shows 97% of general areas meet DAQ 3.0, but one interior exit stairway fails. The AHJ has designated exit stairs as critical areas. What is the result for that floor?
Answer: Fail, because critical areas need 99% coverage. IFC Section 510 and NFPA 1225 require coverage in 95% of general areas and 99% in critical areas such as fire command centers, fire pump rooms, exit stairs, exit passageways and elevator lobbies. The general areas pass, but a failed stairway means the critical area figure isn't met. The design must add coverage in the stair before acceptance.
8. An indoor panel antenna's data sheet lists a gain of 8 dBd. What is its gain in dBi?
Answer: 10.15 dBi. A half-wave dipole has 2.15 dB of gain over an isotropic radiator, so dBi = dBd + 2.15, giving 10.15 dBi. Subtracting 2.15 is the common mistake. Always compare antennas and calculate EIRP in the same unit, usually dBi.
9. After a public safety BDA goes into service, the agency's radio shop reports a raised noise floor on its donor site receivers, hurting talk-in from portables across the area. What is the most likely cause?
Answer: BDA uplink gain set too high. A BDA's uplink amplifies its own noise plus building noise and sends it to the donor site; with too much uplink gain this raises the site's noise floor and desensitizes its receivers for everyone. Set uplink gain to balance the system with the minimum needed, per the licensee. Aiming at the donor site is correct, and downlink gain doesn't add noise at the site.
10. A site survey picks a distant donor site for an off-air BDA system. Which donor antenna arrangement is normally used?
Answer: A roof-mounted Yagi aimed at the donor site. A directional donor antenna on the roof pointed at the chosen donor site gives a strong, clean donor signal and rejects other sites and interference. Its back-to-front ratio and placement also help isolation from the indoor antennas. An indoor omni sees weak, mixed signals and couples with the distribution antennas.
11. Coaxial cable for a DAS will run above a suspended ceiling that is used as a return-air space. What cable rating is required?
Answer: Plenum-rated cable (CMP or CATVP). A space used for environmental air is a plenum, and the NEC requires plenum-rated cable there, or cable in an approved raceway, because of the fire and smoke risk. Riser cable is rated for vertical shafts between floors, and general-purpose cable for other spaces. Plenum cable may replace riser or general cable, not the reverse.
12. A remote unit outputs +20 dBm. It feeds 6 dB of coax loss and a 2-way splitter with 3.5 dB loss to an antenna with 3 dBi gain. What is the EIRP from that antenna?
Answer: 13.5 dBm. Work in dB: +20 dBm - 6 dB coax - 3.5 dB splitter + 3 dBi antenna gain = 13.5 dBm EIRP. A real 2-way split is a little over the ideal 3 dB because of insertion loss. Adding losses instead of subtracting them is the usual error.
13. A 10 dB directional coupler (tapper) receives +30 dBm at its input. Ignoring its small insertion loss, about what leaves the coupled and through ports?
Answer: 20 dBm coupled and about 29.5 dBm through. The coupled port is 10 dB below the input, +20 dBm (1 W becomes 0.1 W). The through port keeps the remaining 0.9 W, which is only about 0.46 dB lower, about +29.5 dBm. Couplers let a designer feed a small share to a nearby antenna while most power continues down the line.
14. During BDA commissioning, isolation between the donor antenna and the closest indoor antenna measures 85 dB. Under NFPA 1225, what is the maximum booster gain allowed?
Answer: 65 dB. NFPA 1225 requires donor to indoor antenna isolation of at least 20 dB above the system gain, so gain can be at most 85 - 20 = 65 dB. Gain close to or above the isolation causes feedback oscillation that can jam the public safety system. If more gain is needed, improve isolation first by moving or shielding antennas.
15. A PIM test on a newly installed cellular DAS antenna run fails. Sweep tests for return loss and distance-to-fault look normal. What is the most likely cause?
Answer: A loose, dirty or under-torqued connector. Passive intermodulation comes from nonlinear junctions, such as loose, dirty or under-torqued connectors, or rusty or loose metal near an antenna, which mix strong carriers into interfering products. These faults may not show on a return loss sweep. Clean, re-terminate or torque connectors to spec and clear metal objects, then retest.

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ETA DAS exam FAQ

How many questions are on the ETA DAS exam?

75 multiple-choice questions, with a time limit of 2 hours. Format: closed book; scratch paper and a non-programmable calculator are allowed. no hands-on exam is required for das.

What is the passing score for ETA DAS?

75%.

How much does the ETA DAS exam cost?

US$105, with one free retake within one year of the first sitting. 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 DAS exam offered in?

English. ETA does not list other languages for DAS; confirm with ETA.

Where do I take the ETA DAS exam?

Any ETA Certification Administrator (test sites at schools, colleges and military bases), online through Trapeza or on paper, or remotely proctored through ETA's partner ExamRoom.AI for an extra fee.

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

What's in the premium ETA DAS prep?

3,000 practice questions organized topic by topic (DAS Fundamentals and Types: 375; Spectrum, Radio Systems and FCC Rules: 375; Safety and RF Exposure: 375; Building Codes and Public Safety Requirements: 375; RF Signal Characteristics, Decibels and Noise: 375; Site Surveys and DAS Equipment: 375; Antennas, Transmission Lines and Passive Components: 375; Installation, Commissioning, Testing and Troubleshooting: 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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