ACE 2026/2027 NCTI PROGRESSION FIELD TECH 4
PRACTICE QUESTIONS AND ANSWERS GRADED A+
◉ What must a technician be aware of when analyzing a digital TV
(DTV) problem? Answer: There is frequently more than one
contributor to a specific DTV service problem.
◉ After a digital TV (DTV) service problem has been analyzed and
possible causes considered, what is accomplished by isolating the
various network elements? Answer: It narrows the scope of likely
problem sources.
◉ During which step of the six-step troubleshooting process for a
digital TV (DTV) service problem are quadrature amplitude
modulation (QAM) channel measurements typically taken? Answer:
Diagnosing symptoms.
◉ When replacing a splitter to resolve a digital TV (DTV) service
problem, what does confirming the splitter output levels before
attaching the output connectors do? Answer: Confirmation
reinforces the technician's confidence that the problem will be
resolved by replacing the splitter.
◉ Which of the following digital TV (DTV) trouble calls could have
been avoided with customer education about the product? Answer:
The digital set-top box (STB) overheats.
,◉ When troubleshooting a digital TV (DTV) authorization issue,
what can be verified using the set-top box (STB) diagnostic page?
Answer: STB reception of authorization message data.
◉ Which type of set-top box (STB) operates more like Data Over
Cable Service Interface Specification (DOCSIS) cable modems with
return channels on the same frequencies used for cable modems?
Answer: STB with DOCSIS Set-top Gateway (DSG) client software
and embedded DOCSIS modems.
◉ Because the spectral density of a quadrature amplitude
modulation (QAM) channel is much higher than that of an analog TV
channel, what is done to ensure equal power in all channels in a
network with analog and digital modulation channels? Answer:
Operate the analog TV channels at higher amplitude level than the
QAM channels.
◉ What does a set-top box (STB) diagnostic page of a quadrature
amplitude modulation (QAM) channel showing signal-to-noise ratio
(SNR) near or below 30 dB indicate? Answer: The QAM channel
quality is on the edge for reliable reception, and the source of the
problem is likely in the distribution network or customer premises.
◉ Which Data over Cable Service Interface Specification (DOCSIS)
layer is used by the cable modem termination system (CMTS) to
differentiate between cable modems? Answer: The DOCSIS Media
Access Control (MAC) Layer.
, ◉ What was introduced in Data Over Cable Service Interface
Specification (DOCSIS) 3.0 to allow enough bandwidth for upstream
carriers from previous DOCSIS versions? Answer: The option to
increase the top frequency of the upstream to 85 MHz.
◉ In a Data Over Cable Service Interface Specification (DOCSIS)
network, why is the data throughput over the return or upstream
path typically less than the throughput of data over the forward or
downstream path? Answer: Compared to the downstream path, the
narrower bandwidths and lower orders of modulation used to
transport data over the return path cause the downstream and
upstream data throughput to be unequal or asymmetrical.
◉ What would be the downstream throughput if two quadrature
amplitude modulation (QAM) channels with a throughput of 38
megabits per second (Mbps) were bonded? Answer: 76 Mbps.
◉ What are two features that were added in Data Over Cable Service
Interface Specification (DOCSIS) 3.1 to extend the viability of hybrid
fiber/coax (HFC) networks into the next decade? Answer:
Orthogonal frequency division multiplexing (OFDM) and lowdensity
parity-check (LDPC).
◉ How does Internet protocol (IP) multicast differ from IP
broadcast? Answer: IP multicast traffic is only sent to specific
modem addresses on the network; IP broadcast traffic is sent to all
modems on the network.
PRACTICE QUESTIONS AND ANSWERS GRADED A+
◉ What must a technician be aware of when analyzing a digital TV
(DTV) problem? Answer: There is frequently more than one
contributor to a specific DTV service problem.
◉ After a digital TV (DTV) service problem has been analyzed and
possible causes considered, what is accomplished by isolating the
various network elements? Answer: It narrows the scope of likely
problem sources.
◉ During which step of the six-step troubleshooting process for a
digital TV (DTV) service problem are quadrature amplitude
modulation (QAM) channel measurements typically taken? Answer:
Diagnosing symptoms.
◉ When replacing a splitter to resolve a digital TV (DTV) service
problem, what does confirming the splitter output levels before
attaching the output connectors do? Answer: Confirmation
reinforces the technician's confidence that the problem will be
resolved by replacing the splitter.
◉ Which of the following digital TV (DTV) trouble calls could have
been avoided with customer education about the product? Answer:
The digital set-top box (STB) overheats.
,◉ When troubleshooting a digital TV (DTV) authorization issue,
what can be verified using the set-top box (STB) diagnostic page?
Answer: STB reception of authorization message data.
◉ Which type of set-top box (STB) operates more like Data Over
Cable Service Interface Specification (DOCSIS) cable modems with
return channels on the same frequencies used for cable modems?
Answer: STB with DOCSIS Set-top Gateway (DSG) client software
and embedded DOCSIS modems.
◉ Because the spectral density of a quadrature amplitude
modulation (QAM) channel is much higher than that of an analog TV
channel, what is done to ensure equal power in all channels in a
network with analog and digital modulation channels? Answer:
Operate the analog TV channels at higher amplitude level than the
QAM channels.
◉ What does a set-top box (STB) diagnostic page of a quadrature
amplitude modulation (QAM) channel showing signal-to-noise ratio
(SNR) near or below 30 dB indicate? Answer: The QAM channel
quality is on the edge for reliable reception, and the source of the
problem is likely in the distribution network or customer premises.
◉ Which Data over Cable Service Interface Specification (DOCSIS)
layer is used by the cable modem termination system (CMTS) to
differentiate between cable modems? Answer: The DOCSIS Media
Access Control (MAC) Layer.
, ◉ What was introduced in Data Over Cable Service Interface
Specification (DOCSIS) 3.0 to allow enough bandwidth for upstream
carriers from previous DOCSIS versions? Answer: The option to
increase the top frequency of the upstream to 85 MHz.
◉ In a Data Over Cable Service Interface Specification (DOCSIS)
network, why is the data throughput over the return or upstream
path typically less than the throughput of data over the forward or
downstream path? Answer: Compared to the downstream path, the
narrower bandwidths and lower orders of modulation used to
transport data over the return path cause the downstream and
upstream data throughput to be unequal or asymmetrical.
◉ What would be the downstream throughput if two quadrature
amplitude modulation (QAM) channels with a throughput of 38
megabits per second (Mbps) were bonded? Answer: 76 Mbps.
◉ What are two features that were added in Data Over Cable Service
Interface Specification (DOCSIS) 3.1 to extend the viability of hybrid
fiber/coax (HFC) networks into the next decade? Answer:
Orthogonal frequency division multiplexing (OFDM) and lowdensity
parity-check (LDPC).
◉ How does Internet protocol (IP) multicast differ from IP
broadcast? Answer: IP multicast traffic is only sent to specific
modem addresses on the network; IP broadcast traffic is sent to all
modems on the network.
