WGU D413 Telecommunications & Wireless
Communications Exam 2026 | Latest Updated Practice
Questions & Answers | 100+ Q&A
1. Which multiplexing technique divides a communication channel into separate
frequency bands?
A. TDM
B. FDM
C. CDM
D. WDM
Correct Answer: B. FDM
Explanation: Frequency-division multiplexing (FDM) assigns different frequency ranges to
separate signals so multiple transmissions can share the same physical medium
simultaneously.
2. Which multiplexing technique assigns different time slots to multiple signals?
A. FDM
B. WDM
C. TDM
D. CDMA
,Correct Answer: C. TDM
Explanation: Time-division multiplexing (TDM) allows multiple signals to use the same
channel by assigning each signal a specific time slot.
3. What is the primary advantage of fiber-optic cable over copper cable?
A. Lower installation complexity
B. Immunity to electromagnetic interference
C. Ability to transmit electrical power
D. Easier termination
Correct Answer: B. Immunity to electromagnetic interference
Explanation: Fiber transmits information as light rather than electrical signals, making it
highly resistant to electromagnetic and radio-frequency interference.
4. Which fiber type generally supports the longest transmission distances?
A. Multimode fiber
B. Single-mode fiber
C. Coaxial fiber
D. Twinaxial fiber
Correct Answer: B. Single-mode fiber
,Explanation: Single-mode fiber has a very small core and allows essentially one
propagation mode, making it suitable for high bandwidth and long-distance communication.
5. Which wavelength is commonly associated with long-distance single-mode fiber
communication?
A. 850 nm
B. 950 nm
C. 1310 nm
D. 1550 nm
Correct Answer: D. 1550 nm
Explanation: 1550 nm is widely used for long-distance optical transmission because
attenuation is relatively low at this wavelength.
6. Which fiber type is commonly associated with an 850 nm optical wavelength?
A. Single-mode fiber
B. Multimode fiber
C. Coaxial cable
D. Twisted-pair cable
Correct Answer: B. Multimode fiber
Explanation: 850 nm is commonly used with multimode fiber, particularly in shorter-distance
data-center and LAN applications.
, 7. What is the primary purpose of shielding in a cable?
A. Increase IP addressing capacity
B. Reduce electromagnetic interference
C. Increase electrical resistance
D. Convert analog signals to digital signals
Correct Answer: B. Reduce electromagnetic interference
Explanation: Shielding helps prevent external electromagnetic interference from affecting
signals carried by the cable.
8. Which cable uses a central conductor surrounded by insulation and a conductive
shield?
A. UTP
B. STP
C. Coaxial
D. Fiber-optic
Correct Answer: C. Coaxial
Explanation: Coaxial cable consists of a central conductor, dielectric insulation, shielding,
and an outer protective jacket.
Communications Exam 2026 | Latest Updated Practice
Questions & Answers | 100+ Q&A
1. Which multiplexing technique divides a communication channel into separate
frequency bands?
A. TDM
B. FDM
C. CDM
D. WDM
Correct Answer: B. FDM
Explanation: Frequency-division multiplexing (FDM) assigns different frequency ranges to
separate signals so multiple transmissions can share the same physical medium
simultaneously.
2. Which multiplexing technique assigns different time slots to multiple signals?
A. FDM
B. WDM
C. TDM
D. CDMA
,Correct Answer: C. TDM
Explanation: Time-division multiplexing (TDM) allows multiple signals to use the same
channel by assigning each signal a specific time slot.
3. What is the primary advantage of fiber-optic cable over copper cable?
A. Lower installation complexity
B. Immunity to electromagnetic interference
C. Ability to transmit electrical power
D. Easier termination
Correct Answer: B. Immunity to electromagnetic interference
Explanation: Fiber transmits information as light rather than electrical signals, making it
highly resistant to electromagnetic and radio-frequency interference.
4. Which fiber type generally supports the longest transmission distances?
A. Multimode fiber
B. Single-mode fiber
C. Coaxial fiber
D. Twinaxial fiber
Correct Answer: B. Single-mode fiber
,Explanation: Single-mode fiber has a very small core and allows essentially one
propagation mode, making it suitable for high bandwidth and long-distance communication.
5. Which wavelength is commonly associated with long-distance single-mode fiber
communication?
A. 850 nm
B. 950 nm
C. 1310 nm
D. 1550 nm
Correct Answer: D. 1550 nm
Explanation: 1550 nm is widely used for long-distance optical transmission because
attenuation is relatively low at this wavelength.
6. Which fiber type is commonly associated with an 850 nm optical wavelength?
A. Single-mode fiber
B. Multimode fiber
C. Coaxial cable
D. Twisted-pair cable
Correct Answer: B. Multimode fiber
Explanation: 850 nm is commonly used with multimode fiber, particularly in shorter-distance
data-center and LAN applications.
, 7. What is the primary purpose of shielding in a cable?
A. Increase IP addressing capacity
B. Reduce electromagnetic interference
C. Increase electrical resistance
D. Convert analog signals to digital signals
Correct Answer: B. Reduce electromagnetic interference
Explanation: Shielding helps prevent external electromagnetic interference from affecting
signals carried by the cable.
8. Which cable uses a central conductor surrounded by insulation and a conductive
shield?
A. UTP
B. STP
C. Coaxial
D. Fiber-optic
Correct Answer: C. Coaxial
Explanation: Coaxial cable consists of a central conductor, dielectric insulation, shielding,
and an outer protective jacket.
