VDV Network Infrastructure 3 — Questions and Answers
Question 1: What is the minimum bend radius for a 4-pair UTP Cat6 cable during installation?
- 1 times the cable diameter
- 4 times the cable diameter (Correct answer)
- 8 times the cable diameter
- 12 times the cable diameter
Correct answer: 4 times the cable diameter
TIA-568 specifies a minimum bend radius of 4 times the cable's outer diameter for 4-pair UTP during and after installation.
Question 2: In a VoIP deployment over a converged network, what mechanism is used to prioritize voice traffic over data?
- VLAN tagging only
- Quality of Service (QoS) (Correct answer)
- Spanning Tree Protocol (STP)
- NAT overload
Correct answer: Quality of Service (QoS)
QoS mechanisms classify and prioritize voice packets to ensure low latency and jitter, which are critical for intelligible VoIP calls.
Question 3: A technician measures -3.5 dB insertion loss on a fiber run. What does this indicate?
- The fiber has failed and must be replaced
- Signal loss is within acceptable limits for most applications (Correct answer)
- The connector is reversed
- Chromatic dispersion has exceeded the threshold
Correct answer: Signal loss is within acceptable limits for most applications
An insertion loss of -3.5 dB is within the acceptable range for most short-distance fiber links, as budgets commonly allow up to -3 dB per connector and more for the total link.
Question 4: What does OTDR stand for and what is its primary use?
- Optical Time Domain Reflectometer — locates faults and measures loss in fiber cables (Correct answer)
- Optical Tone Detection Receiver — identifies cable tone signals
- Output Transfer Data Relay — routes fiber signals between switches
- Optical Test Data Recorder — logs test results to a database
Correct answer: Optical Time Domain Reflectometer — locates faults and measures loss in fiber cables
An OTDR sends light pulses into fiber and analyzes reflections to locate faults, splices, and connectors, and measure distance and loss.
Question 5: Which cable category is the minimum required to support 10GBASE-T Ethernet up to 55 meters?
- Cat5e
- Cat6 (Correct answer)
- Cat6A
- Cat7
Correct answer: Cat6
Cat6 cable supports 10GBASE-T up to 55 meters, while Cat6A extends this to the full 100-meter channel length.
Question 6: What is the maximum number of cables allowed in a horizontal cable bundle before fire code requires separation or conduit?
- 12
- 24
- It depends on the cable type and applicable NEC/local code (Correct answer)
- 50
Correct answer: It depends on the cable type and applicable NEC/local code
The NEC and local fire codes dictate bundling limits, which vary by cable rating (CM, CMR, CMP) and installation location, with no single universal number.
Question 7: When using a cable certifier, what parameter confirms the cable can support the intended application (e.g., Cat6 1G Ethernet)?
- Continuity pass only
- PASS result against the applicable TIA or ISO channel standard (Correct answer)
- Wire map showing all 8 pins connected
- Attenuation below 20 dB at 100 MHz
Correct answer: PASS result against the applicable TIA or ISO channel standard
A cable certifier must show a PASS result against the relevant TIA-568 or ISO 11801 standard, which tests all required parameters simultaneously.
VDV Network Infrastructure 3
What is the minimum bend radius for a 4-pair UTP Cat6 cable during installation?