WGU D413 – Telecommunications & Wireless
Communications Objective Assessment | OA V1
and V2 | Questions and Answers | 2026 Update
1. Which OSI layer is responsible for reliable data delivery, error detection,
and retransmission?
CORRECT ANSWER: Transport (Layer 4) – Rationale: The Transport
layer (e.g., TCP) manages error detection, retransmission, flow control, and
segmentation. Reliability is not handled at the Network or Data Link layers.
2. A network technician needs to divide a network into multiple smaller
segments, each with the same number of hosts. What type of subnetting is
being applied?
CORRECT ANSWER: Fixed-Length Subnet Mask (FLSM) – Rationale:
FLSM uses equal-length subnet masks so each subnet has the same
number of hosts, simplifying routing tables and network design .
3. Which component converts digital signals into analog signals for
transmission over traditional phone lines?
CORRECT ANSWER: Modem – Rationale: A modem (modulator-
demodulator) converts digital data to analog for transmission and back
again for reception over analog phone lines .
4. What is the primary purpose of multiplexing in telecommunications?
CORRECT ANSWER: Combining multiple signals into one channel –
Rationale: Multiplexing allows multiple data streams to share a single
transmission medium, improving efficiency and reducing the need for
separate channels .
,5. Which transmission medium provides the highest bandwidth and lowest
signal loss, while also being immune to electromagnetic interference?
CORRECT ANSWER: Fiber-optic cable – Rationale: Fiber-optic cables
transmit data as light, offering extremely high bandwidth, minimal signal
loss over long distances, and complete immunity to EMI .
6. What is the primary purpose of a subnet mask in IP networking?
CORRECT ANSWER: Define which portion of an IP address is the
network and which is the host – Rationale: Subnet masks divide an IP
address into network and host portions, allowing proper routing and
subnetting .
7. Which wireless technology operates in both the 2.4 GHz and 5 GHz
frequency bands and is commonly used for local area networking?
CORRECT ANSWER: Wi-Fi – Rationale: Wi-Fi (IEEE 802.11 standards)
commonly uses both the 2.4 GHz and 5 GHz frequency bands for wireless
local area network connectivity .
8. What does latency measure in a network?
CORRECT ANSWER: Delay in transmission – Rationale: Latency is the
time delay between sending and receiving data, typically measured in
milliseconds .
9. Which communication mode allows simultaneous two-way transmission
over a single link?
CORRECT ANSWER: Full-duplex – Rationale: Full-duplex communication
allows simultaneous bi-directional data transmission, improving throughput
and efficiency .
, 10. Which type of switching establishes a dedicated communication path
for the entire session?
CORRECT ANSWER: Circuit switching – Rationale: Circuit switching
creates a dedicated channel for the entire session duration, as used in
traditional telephone networks .
11. What is the primary function of a network switch?
CORRECT ANSWER: Forward data packets to the correct device on a
local network using MAC addresses – Rationale: Switches operate at
Layer 2 of the OSI model, using MAC addresses to filter and forward
frames to specific destination ports .
12. Which protocol is primarily used for secure file transfer over a network,
encrypting both commands and data?
CORRECT ANSWER: SFTP (Secure File Transfer Protocol) – Rationale:
SFTP encrypts both commands and data, unlike FTP which transmits data
in plaintext .
13. Which IEEE standard defines Wi-Fi networks?
CORRECT ANSWER: 802.11 – Rationale: The IEEE 802.11 family of
standards defines wireless local area network (WLAN) technologies,
commonly known as Wi-Fi .
14. What is the purpose of a default gateway in networking?
CORRECT ANSWER: Route traffic from a local network to other
networks – Rationale: A default gateway serves as a routing device that
forwards traffic destined for other networks outside the local subnet .
Communications Objective Assessment | OA V1
and V2 | Questions and Answers | 2026 Update
1. Which OSI layer is responsible for reliable data delivery, error detection,
and retransmission?
CORRECT ANSWER: Transport (Layer 4) – Rationale: The Transport
layer (e.g., TCP) manages error detection, retransmission, flow control, and
segmentation. Reliability is not handled at the Network or Data Link layers.
2. A network technician needs to divide a network into multiple smaller
segments, each with the same number of hosts. What type of subnetting is
being applied?
CORRECT ANSWER: Fixed-Length Subnet Mask (FLSM) – Rationale:
FLSM uses equal-length subnet masks so each subnet has the same
number of hosts, simplifying routing tables and network design .
3. Which component converts digital signals into analog signals for
transmission over traditional phone lines?
CORRECT ANSWER: Modem – Rationale: A modem (modulator-
demodulator) converts digital data to analog for transmission and back
again for reception over analog phone lines .
4. What is the primary purpose of multiplexing in telecommunications?
CORRECT ANSWER: Combining multiple signals into one channel –
Rationale: Multiplexing allows multiple data streams to share a single
transmission medium, improving efficiency and reducing the need for
separate channels .
,5. Which transmission medium provides the highest bandwidth and lowest
signal loss, while also being immune to electromagnetic interference?
CORRECT ANSWER: Fiber-optic cable – Rationale: Fiber-optic cables
transmit data as light, offering extremely high bandwidth, minimal signal
loss over long distances, and complete immunity to EMI .
6. What is the primary purpose of a subnet mask in IP networking?
CORRECT ANSWER: Define which portion of an IP address is the
network and which is the host – Rationale: Subnet masks divide an IP
address into network and host portions, allowing proper routing and
subnetting .
7. Which wireless technology operates in both the 2.4 GHz and 5 GHz
frequency bands and is commonly used for local area networking?
CORRECT ANSWER: Wi-Fi – Rationale: Wi-Fi (IEEE 802.11 standards)
commonly uses both the 2.4 GHz and 5 GHz frequency bands for wireless
local area network connectivity .
8. What does latency measure in a network?
CORRECT ANSWER: Delay in transmission – Rationale: Latency is the
time delay between sending and receiving data, typically measured in
milliseconds .
9. Which communication mode allows simultaneous two-way transmission
over a single link?
CORRECT ANSWER: Full-duplex – Rationale: Full-duplex communication
allows simultaneous bi-directional data transmission, improving throughput
and efficiency .
, 10. Which type of switching establishes a dedicated communication path
for the entire session?
CORRECT ANSWER: Circuit switching – Rationale: Circuit switching
creates a dedicated channel for the entire session duration, as used in
traditional telephone networks .
11. What is the primary function of a network switch?
CORRECT ANSWER: Forward data packets to the correct device on a
local network using MAC addresses – Rationale: Switches operate at
Layer 2 of the OSI model, using MAC addresses to filter and forward
frames to specific destination ports .
12. Which protocol is primarily used for secure file transfer over a network,
encrypting both commands and data?
CORRECT ANSWER: SFTP (Secure File Transfer Protocol) – Rationale:
SFTP encrypts both commands and data, unlike FTP which transmits data
in plaintext .
13. Which IEEE standard defines Wi-Fi networks?
CORRECT ANSWER: 802.11 – Rationale: The IEEE 802.11 family of
standards defines wireless local area network (WLAN) technologies,
commonly known as Wi-Fi .
14. What is the purpose of a default gateway in networking?
CORRECT ANSWER: Route traffic from a local network to other
networks – Rationale: A default gateway serves as a routing device that
forwards traffic destined for other networks outside the local subnet .
