- The ETA Data Cabling Installer (DCI) competency outline lists 22 major knowledge categories, from Safety through Documentation.
- The written exam has 75 multiple-choice questions, 2 hours, a 75% passing score, and costs USD $155.
- ETA publishes no percentage weights for the 22 domains, so study all of them rather than guessing which count most.
- Certification also requires an ETA-approved hands-on training course and practical assessment; the written exam alone is not enough.
How the Official Outline Is Organized
The Data Cabling Installer credential from ETA International is defined by a competency document that groups everything a candidate must know into 22 major knowledge categories. This guide walks through every one of them, in the order ETA lists them, and explains what each is likely to ask of you. If you are brand new to the credential, start with What Is DCI Certification? to confirm you are looking at the right program, then return here.
One point of clarity: "DCI" appears as an acronym for several unrelated credentials. Throughout this site, and in this article, it means only the ETA Data Cabling Installer certification. DCI is a stand-alone ETA credential and does not require the Associate CET (CETa) credential first.
Exam Format and Registration Facts
Before diving into domains, anchor yourself in the mechanics. Candidates face a written examination of 75 multiple-choice questions with a 2-hour limit. The required score is 75%, which works out to 57 correct answers out of 75. For a deeper look at what that threshold means in practice, see DCI Passing Score 2026: Exactly What You Need to Pass.
| Item | Detail |
|---|---|
| Credential | Data Cabling Installer (DCI), ETA International |
| Written exam fee | USD $155 |
| Questions / time | 75 multiple-choice / 2 hours |
| Passing score | 75% |
| Retake policy | One free retake within one year of the first examination |
| Testing options | Trapeza online testing or paper exams via ETA Certification Administrators; ETA's FAQ also lists Exam Room.AI remote proctoring |
| Permitted items | Photo ID required; scratch paper and a nonprogrammable scientific calculator allowed |
| Certification term | Four years |
Two details trip people up. First, certification requires more than the written exam: you also need an ETA-approved hands-on training course and practical assessment. Remote written testing does not remove that practical requirement, and the 2-hour exam timer says nothing about how long your training course runs. Second, the nonprogrammable scientific calculator matters because several domains, especially electricity and cable performance, involve arithmetic. Our DCI Requirements 2026 article covers eligibility in more depth, and DCI Certification Cost 2026 breaks down the full spend beyond the $155 exam fee.
Foundations: Domains 1-5
The first five domains build the vocabulary and math you will lean on for the rest of the outline. They are easy to underestimate because they feel like "intro material," but questions drawn from them often reappear embedded inside installation and testing scenarios.
Domain 1: Safety
Expect questions on protecting yourself and others while working in ceilings, risers, and equipment rooms.
- Personal protective equipment and safe tool handling
- Ladder, lift, and overhead-work awareness
- Recognizing electrical and environmental hazards on a job site
Domain 2: Basic Electricity
This is where your calculator earns its place. Know the relationships among voltage, current, resistance, and power, and be ready to work simple circuit problems.
- Ohm's law and power calculations
- Series versus parallel behavior
- Units, prefixes, and unit conversion
Domain 3: Data Cabling Introduction
A orientation to what structured cabling is for and the types of media and systems you will encounter.
Domain 4: Data Communications Basics
Core networking concepts: how data is represented, transmitted, and organized into layers and signals.
- Analog versus digital signaling
- Bandwidth, bit rate, and related terminology
- Network models and protocol concepts at a working-installer level
Domain 5: Cabling Specifications and Standards
Who writes the rules and what they say. Learn which standards bodies govern cabling and what category and performance designations mean.
- Standards organizations and their roles
- Category ratings and the performance each implies
- Distance and channel/link concepts
If the math in Domain 2 worries you, note that the difficulty of this credential usually comes from breadth rather than depth. Our How Hard Is the DCI Exam? guide discusses where candidates actually struggle.
Architecture and Components: Domains 6-10
Network and Cable Fundamentals
Domain 6: Basic Network Design: Architecture and Implementation
How networks are laid out and how cabling supports them.
- Topologies and how they map onto physical cabling
- The relationship between logical design and the physical plant
Domain 7: Cable Construction
What is physically inside the jacket and why it matters.
- Conductors, insulation, twisting, shielding, and jacketing
- Differences between solid and stranded conductors and where each is used
- Basic fiber construction: core, cladding, and coatings
Domain 8: Cable Performance Characteristics
The measurable behaviors that determine whether a link works. These concepts return in testing and troubleshooting questions, so master them here.
- Attenuation and its causes
- Crosstalk (near-end and far-end) and related parameters
- Return loss, impedance, and noise concepts
Codes and Structure
Domain 9: National Electrical Code® and Underwriters Laboratories® Requirements
The regulatory layer. Know why cable has fire-performance ratings and where each type may be installed.
- Plenum, riser, and general-purpose cable distinctions
- Firestopping concepts and penetrations
- The role of listing and labeling
Domain 10: Telecommunications Cabling System Structure
The standard building blocks of a structured cabling system, from entrance facility to work area.
- Entrance facility, equipment room, backbone, horizontal, and telecommunications room roles
- Where each subsystem begins and ends
Tools, Media, and Outlets: Domains 11-16
Domain 11: Data Cabling Installer Tools
Know the tool, its purpose, and its correct use.
- Cable strippers, punch-down tools, and crimpers
- Pulling aids and basic test instruments
- Proper handling and common misuse
Domain 12: Transmission Media for Networking and Telecommunications
The media options and when each is chosen.
- Twisted-pair copper, coaxial, and optical fiber
- Strengths, limits, and typical applications of each
Domain 13: Work Area Telecommunications Outlet and Connectors
The user-facing end of the system.
- Outlet types and connector styles
- Pin and pair assignments and termination schemes
Domain 14: Local Area Network Interconnection and Internetworking
How separate networks and segments are linked together.
- Repeaters, hubs, switches, bridges, and routers at a conceptual level
- What each device does to traffic
Domain 15: Wireless Heterogeneous Cabling Networks
Where wireless meets the cabled infrastructure.
- How wireless access relies on the wired backbone
- Cabling considerations when supporting wireless equipment
Domain 16: Cabling System Components
The passive hardware that makes a system manageable.
- Patch panels, cross-connects, racks, and cable management
- Patch cords versus permanent-link cabling
Design, Installation, and Testing: Domains 17-22
The last six domains are the most job-like. If you plan to work in this field, these are the domains that most resemble a day on site, which is relevant if you are researching DCI jobs and what employers expect.
Domain 17: Cabling System Design
Planning a system before any cable is pulled.
- Pathway and space planning
- Length limits and capacity considerations
Domain 18: Cabling Installation
Practical technique for placing cable without damaging it.
- Pulling tension and bend-radius limits
- Support, routing, and separation from power wiring
- Labeling during installation
Domain 19: Connector Installation
Terminating correctly, because a poor termination ruins a good cable.
- Maintaining pair twist close to the termination point
- Wiring schemes and consistency across both ends
- Basic fiber connector concepts
Domain 20: Cabling Testing and Certification
Proving the installed link meets its target.
- Continuity and wire-map tests
- Length, attenuation, and crosstalk measurements
- Interpreting pass/fail results against a standard
Domain 21: Cabling Troubleshooting
Reasoning from symptom to cause.
- Opens, shorts, split pairs, and reversed pairs
- Excessive length and connector faults
- A logical sequence for isolating a failing link
Domain 22: Documentation
The record that makes a system maintainable.
- Labeling schemes and records
- As-built drawings and test result retention
Key Takeaway
Domains 8, 18, 19, 20, and 21 form a connected chain: performance characteristics explain why a test fails, installation and termination technique explain how it came to fail, and troubleshooting is the method for finding it. Study them as one story, not five separate lists.
The Weighting Question
Candidates often ask which domains carry the most exam weight. The honest answer is that ETA's competency document lists the 22 major headings without publishing a percentage allocation, and we do not infer weights that were never supplied. Anyone quoting precise per-domain percentages for this exam is guessing.
The practical consequence is simple: with 75 questions spread across 22 categories, you cannot safely skip any domain. A weak area is a liability even if it is only a handful of questions. For context on how candidates fare overall, see DCI Pass Rate 2026: What the Data Shows, and for the complete preparation approach, read the DCI Study Guide 2026.
Sequencing the 22 Domains
Rather than a generic study schedule, order your effort by dependency. Concepts in early domains are prerequisites for later ones, so this sequencing keeps each week building on the last.
Math and vocabulary (Domains 1-5)
- Drill Ohm's law and unit conversion with your permitted calculator
- Learn standards bodies and category designations
Physical cable and codes (Domains 6-10)
- Memorize cable construction and performance terms
- Pair each cable rating with where it may be installed
Hardware and media (Domains 11-16)
- Match each tool to its task
- Compare copper, coax, and fiber by use case
Applied skills (Domains 17-22)
- Practice calculation and troubleshooting scenarios
- Review documentation conventions, then take timed practice sets
Finish by running full 75-question timed sets in the DCI practice test environment so the 2-hour pacing feels routine. Aim for roughly 90 seconds per question on average, and flag calculation items to return to after the easier recall questions. A free practice exam is a good way to find which of the 22 domains needs another pass, and our DCI Cheat Sheet condenses the must-know facts for a final review.
Frequently Asked Questions
ETA's competency outline for the Data Cabling Installer lists 22 major knowledge categories, beginning with Safety and ending with Documentation. The written exam itself contains 75 multiple-choice questions drawn from across that scope.
No official percentage allocation is supplied for the 22 domains, so we do not assign weights. Because coverage is broad, plan to study every domain instead of concentrating on a few.
No. Certification also requires an ETA-approved hands-on training course and practical assessment. Taking the written exam remotely does not remove that practical requirement. See DCI training for how the hands-on piece fits in.
ETA allows one free retake within one year of the first examination. Use your first attempt's weak areas to direct your review before retaking.
The term is four years. Maintenance with Hands-On requires a maintenance form, 6 continuing-education hours per year (24 over the four years), supervisor-completed employer verification, and USD $25 per year ($100 over the cycle).
Whether the credential pays off for you depends on your local market and employer, and we avoid assuming a guaranteed pay premium. If you are weighing that decision, Is the DCI Certification Worth It? walks through the evidence, and DCI Salary Guide 2026 covers earnings context without overstating it.