VDV Copper Cabling 3 — Questions and Answers
Question 1: When terminating Cat6A cable to an 8P8C (RJ-45) jack, which 110-style punch-down tool setting should be used?
- The low-impact (cut) setting for solid conductors (Correct answer)
- The high-impact setting for stranded conductors
- Either setting produces identical results for Cat6A
- A Krone tool must be used instead of a 110 tool
Correct answer: The low-impact (cut) setting for solid conductors
110-style punch-down tools have a low setting for solid wire (which is used in horizontal cabling) to seat the conductor without over-driving it.
Question 2: What is the function of a cable balun in a copper cabling system?
- Convert between balanced (twisted pair) and unbalanced (coaxial) transmission (Correct answer)
- Amplify the signal at mid-span
- Provide electromagnetic shielding on UTP cable
- Terminate the cable impedance at the far end
Correct answer: Convert between balanced (twisted pair) and unbalanced (coaxial) transmission
A balun (balanced-unbalanced) converts signals between the balanced differential signaling of twisted pair and the unbalanced single-ended signaling of coaxial cable.
Question 3: Which standard governs the testing requirements for Category 6A permanent links and channels?
- ANSI/TIA-568.2-D (Correct answer)
- ANSI/TIA-606-C
- ANSI/TIA-569-D
- IEEE 802.3an
Correct answer: ANSI/TIA-568.2-D
ANSI/TIA-568.2-D defines balanced twisted-pair cabling components, installation practices, and field testing requirements including Cat6A.
Question 4: A 25-pair backbone cable uses what color code system to identify each pair?
- A 5-color tip group combined with a 5-color ring group giving 25 combinations (Correct answer)
- Sequential solid colors numbered 1 through 25
- The T568A color sequence repeated across all pairs
- Pairs are identified only by pair count from the outer sheath
Correct answer: A 5-color tip group combined with a 5-color ring group giving 25 combinations
25-pair cables use a binder color system combining 5 tip colors (white, red, black, yellow, violet) with 5 ring colors (blue, orange, green, brown, slate) to create 25 unique pairs.
Question 5: What is propagation delay in copper cable, and why does it matter for structured cabling?
- The time for a signal to travel from one end to the other; excessive delay causes timing errors in high-speed networks (Correct answer)
- The reduction in signal amplitude along the cable length
- Crosstalk noise generated at the far end of a long run
- The time a connector takes to establish an insulation displacement connection
Correct answer: The time for a signal to travel from one end to the other; excessive delay causes timing errors in high-speed networks
Propagation delay is the transit time of a signal through the cable, and skew between pairs must stay within limits to ensure correct reassembly of parallel data streams.
Question 6: A technician needs to extend a Cat6 run beyond the 90-meter horizontal limit. What is the correct solution under TIA-568?
- Install an intermediate distribution frame (IDF) with an active switch to restart the segment (Correct answer)
- Use Cat6A cable which supports 150-meter runs without a switch
- Install a passive copper repeater at the 90-meter mark
- Splice two Cat6 cables with a barrel connector to extend the run
Correct answer: Install an intermediate distribution frame (IDF) with an active switch to restart the segment
TIA-568 limits horizontal copper runs to 90 meters; longer distances require an active network switch at an IDF to regenerate the signal for a new 90-meter segment.
Question 7: What does 'alien crosstalk' (AXT) specifically describe in a Cat6A cabling installation?
- Interference coupling between adjacent cables in the same bundle or conduit (Correct answer)
- Crosstalk between pairs within a single cable
- Signal leakage from a shield into an unshielded cable nearby
- Interference caused by EMI sources external to the building
Correct answer: Interference coupling between adjacent cables in the same bundle or conduit
Alien crosstalk (AXT) is the unwanted signal coupling from one cable into a neighboring separate cable, which is the primary limiting factor for Cat6A performance in dense bundles.
VDV Copper Cabling 3
When terminating Cat6A cable to an 8P8C (RJ-45) jack, which 110-style punch-down tool setting should be used?