WGU D413 – Telecommunications & Wireless
Communications Objective Assessment | OA V1 and V2 |
Questions and Answers | 2026 Update | 100% Correct!!
2026-updated focus.
Section 1: Fundamentals of Telecommunications
1. Which layer of the OSI model is responsible for end-to-end error recovery and flow
control?
• A) Physical
• B) Data Link
• C) Network
• D) Transport
Answer: D) Transport
Rationale: The Transport Layer (Layer 4) ensures reliable data transfer, error recovery, and
flow control between hosts.
2. In TCP/IP, which protocol provides connectionless, unreliable delivery?
• A) TCP
• B) IP
• C) UDP
• D) ICMP
,Answer: C) UDP
Rationale: UDP (User Datagram Protocol) is connectionless and does not guarantee delivery,
ordering, or error checking.
3. What is the primary function of a repeater in a network?
• A) Filter traffic based on MAC addresses
• B) Regenerate and retime signals
• C) Route packets between networks
• D) Convert analog to digital signals
Answer: B) Regenerate and retime signals
Rationale: A repeater operates at Layer 1 to extend the physical range of a network by
cleaning and amplifying signals.
4. Which modulation technique changes the frequency of the carrier signal to represent
data?
• A) ASK
• B) FSK
• C) PSK
• D) QAM
Answer: B) FSK (Frequency Shift Keying)
Rationale: FSK varies the carrier frequency; used in older modems and some RFID systems.
5. The bandwidth of a signal is defined as:
• A) Maximum data rate in bps
• B) Difference between highest and lowest frequencies
• C) Number of voltage levels used
• D) Time between signal transitions
,Answer: B) Difference between highest and lowest frequencies
Rationale: Bandwidth (in Hz) is the range of frequencies a signal occupies.
6. Which multiplexing technique divides time into slots and assigns each slot to a different
signal?
• A) FDM
• B) WDM
• C) TDM
• D) CDM
Answer: C) TDM (Time Division Multiplexing)
Rationale: TDM allocates fixed time slots per channel; used in T1/E1 lines.
7. Attenuation in a transmission medium refers to:
• A) Signal distortion due to multiple paths
• B) Loss of signal strength over distance
• C) Interference from other signals
• D) Delay in signal arrival
Answer: B) Loss of signal strength over distance
Rationale: Attenuation is measured in dB and is compensated by amplifiers or repeaters.
8. Which cable type is most resistant to electromagnetic interference (EMI)?
• A) UTP
• B) STP
• C) Coaxial
• D) Fiber optic
Answer: D) Fiber optic
Rationale: Fiber uses light, not electricity, so it is immune to EMI.
9. The PSTN (Public Switched Telephone Network) primarily uses which switching technique?
, • A) Circuit switching
• B) Packet switching
• C) Message switching
• D) Cell switching
Answer: A) Circuit switching
Rationale: PSTN establishes a dedicated circuit for the duration of a call.
10. What does the acronym MIMO stand for in wireless communications?
• A) Multiple Input Multiple Output
• B) Modulation Index Maximum Output
• C) Media Interference Mitigation Order
• D) Multi-Interface Modulation Object
Answer: A) Multiple Input Multiple Output
Rationale: MIMO uses multiple antennas at transmitter and receiver to improve data rates
and reliability.
11. Which IEEE standard defines Ethernet over twisted-pair copper cabling (e.g., 1000BASE-
T)?
• A) 802.11
• B) 802.3
• C) 802.15
• D) 802.16
Answer: B) 802.3
Rationale: IEEE 802.3 covers all Ethernet standards, including copper and fiber variants.
12. What is the maximum data rate of a T1 line in the US?
• A) 1.544 Mbps
• B) 2.048 Mbps
Communications Objective Assessment | OA V1 and V2 |
Questions and Answers | 2026 Update | 100% Correct!!
2026-updated focus.
Section 1: Fundamentals of Telecommunications
1. Which layer of the OSI model is responsible for end-to-end error recovery and flow
control?
• A) Physical
• B) Data Link
• C) Network
• D) Transport
Answer: D) Transport
Rationale: The Transport Layer (Layer 4) ensures reliable data transfer, error recovery, and
flow control between hosts.
2. In TCP/IP, which protocol provides connectionless, unreliable delivery?
• A) TCP
• B) IP
• C) UDP
• D) ICMP
,Answer: C) UDP
Rationale: UDP (User Datagram Protocol) is connectionless and does not guarantee delivery,
ordering, or error checking.
3. What is the primary function of a repeater in a network?
• A) Filter traffic based on MAC addresses
• B) Regenerate and retime signals
• C) Route packets between networks
• D) Convert analog to digital signals
Answer: B) Regenerate and retime signals
Rationale: A repeater operates at Layer 1 to extend the physical range of a network by
cleaning and amplifying signals.
4. Which modulation technique changes the frequency of the carrier signal to represent
data?
• A) ASK
• B) FSK
• C) PSK
• D) QAM
Answer: B) FSK (Frequency Shift Keying)
Rationale: FSK varies the carrier frequency; used in older modems and some RFID systems.
5. The bandwidth of a signal is defined as:
• A) Maximum data rate in bps
• B) Difference between highest and lowest frequencies
• C) Number of voltage levels used
• D) Time between signal transitions
,Answer: B) Difference between highest and lowest frequencies
Rationale: Bandwidth (in Hz) is the range of frequencies a signal occupies.
6. Which multiplexing technique divides time into slots and assigns each slot to a different
signal?
• A) FDM
• B) WDM
• C) TDM
• D) CDM
Answer: C) TDM (Time Division Multiplexing)
Rationale: TDM allocates fixed time slots per channel; used in T1/E1 lines.
7. Attenuation in a transmission medium refers to:
• A) Signal distortion due to multiple paths
• B) Loss of signal strength over distance
• C) Interference from other signals
• D) Delay in signal arrival
Answer: B) Loss of signal strength over distance
Rationale: Attenuation is measured in dB and is compensated by amplifiers or repeaters.
8. Which cable type is most resistant to electromagnetic interference (EMI)?
• A) UTP
• B) STP
• C) Coaxial
• D) Fiber optic
Answer: D) Fiber optic
Rationale: Fiber uses light, not electricity, so it is immune to EMI.
9. The PSTN (Public Switched Telephone Network) primarily uses which switching technique?
, • A) Circuit switching
• B) Packet switching
• C) Message switching
• D) Cell switching
Answer: A) Circuit switching
Rationale: PSTN establishes a dedicated circuit for the duration of a call.
10. What does the acronym MIMO stand for in wireless communications?
• A) Multiple Input Multiple Output
• B) Modulation Index Maximum Output
• C) Media Interference Mitigation Order
• D) Multi-Interface Modulation Object
Answer: A) Multiple Input Multiple Output
Rationale: MIMO uses multiple antennas at transmitter and receiver to improve data rates
and reliability.
11. Which IEEE standard defines Ethernet over twisted-pair copper cabling (e.g., 1000BASE-
T)?
• A) 802.11
• B) 802.3
• C) 802.15
• D) 802.16
Answer: B) 802.3
Rationale: IEEE 802.3 covers all Ethernet standards, including copper and fiber variants.
12. What is the maximum data rate of a T1 line in the US?
• A) 1.544 Mbps
• B) 2.048 Mbps
