,WGU D315 OA Exam | Network & Security Foundations
(2026/2027) Q&A | WGU
1. Which OSI layer is primarily responsible for logical addressing and routing packets
between different networks?
A) Physical
B) Data Link
C) Transport
D) Network
Correct Answer: Network
Rationale: The Network layer, Layer 3 of the OSI model, provides logical addressing and
determines paths between networks. IP operates at this layer and routers make forwarding
decisions using network-layer addresses. The Data Link layer handles local frame delivery,
while the Transport layer provides end-to-end transport functions.
2. A network administrator needs a device that forwards Ethernet frames based on
destination MAC addresses. Which device should be selected?
A) Router
B) Switch
C) Modem
D) Repeater
Correct Answer: Switch
Rationale: A switch primarily operates at the Data Link layer and learns MAC addresses
to forward frames toward appropriate ports. Routers make forwarding decisions using
,Layer 3 addresses. Repeaters regenerate signals without examining MAC addresses, while
modems perform signal conversion for communication links.
3. What is the primary function of the Presentation layer in the OSI model?
A) Data formatting and encryption
B) End-to-end delivery
C) Logical addressing
D) Physical transmission
Correct Answer: Data formatting and encryption
Rationale: The Presentation layer, Layer 6, translates and formats data for transmission
and handles encryption and compression. End-to-end delivery is handled by the Transport
layer, logical addressing by the Network layer, and physical transmission by the Physical
layer.
4. Which OSI layer establishes, manages, and terminates connections between applications?
A) Application
B) Transport
C) Session
D) Network
Correct Answer: Session
Rationale: The Session layer, Layer 5, manages connection establishment, session
maintenance, and authentication between applications. The Application layer interfaces
with software, the Transport layer provides end-to-end delivery, and the Network layer
handles routing.
, 5. Which OSI layer transmits raw bitstreams over the physical medium?
A) Data Link
B) Network
C) Transport
D) Physical
Correct Answer: Physical
Rationale: The Physical layer, Layer 1, transmits raw bitstreams over the physical
medium and defines electrical, mechanical, and procedural specifications. The Data Link
layer handles framing, the Network layer handles routing, and the Transport layer provides
end-to-end delivery.
6. What does the Transport layer primarily provide in the OSI model?
A) Logical addressing
B) End-to-end delivery and error recovery
C) Physical transmission
D) Data formatting
Correct Answer: End-to-end delivery and error recovery
Rationale: The Transport layer, Layer 4, provides end-to-end delivery, flow control, error
recovery, segmentation, and reassembly. Logical addressing is handled by the Network
layer, physical transmission by the Physical layer, and data formatting by the Presentation
layer.
7. Which OSI layer interfaces directly with software applications?
(2026/2027) Q&A | WGU
1. Which OSI layer is primarily responsible for logical addressing and routing packets
between different networks?
A) Physical
B) Data Link
C) Transport
D) Network
Correct Answer: Network
Rationale: The Network layer, Layer 3 of the OSI model, provides logical addressing and
determines paths between networks. IP operates at this layer and routers make forwarding
decisions using network-layer addresses. The Data Link layer handles local frame delivery,
while the Transport layer provides end-to-end transport functions.
2. A network administrator needs a device that forwards Ethernet frames based on
destination MAC addresses. Which device should be selected?
A) Router
B) Switch
C) Modem
D) Repeater
Correct Answer: Switch
Rationale: A switch primarily operates at the Data Link layer and learns MAC addresses
to forward frames toward appropriate ports. Routers make forwarding decisions using
,Layer 3 addresses. Repeaters regenerate signals without examining MAC addresses, while
modems perform signal conversion for communication links.
3. What is the primary function of the Presentation layer in the OSI model?
A) Data formatting and encryption
B) End-to-end delivery
C) Logical addressing
D) Physical transmission
Correct Answer: Data formatting and encryption
Rationale: The Presentation layer, Layer 6, translates and formats data for transmission
and handles encryption and compression. End-to-end delivery is handled by the Transport
layer, logical addressing by the Network layer, and physical transmission by the Physical
layer.
4. Which OSI layer establishes, manages, and terminates connections between applications?
A) Application
B) Transport
C) Session
D) Network
Correct Answer: Session
Rationale: The Session layer, Layer 5, manages connection establishment, session
maintenance, and authentication between applications. The Application layer interfaces
with software, the Transport layer provides end-to-end delivery, and the Network layer
handles routing.
, 5. Which OSI layer transmits raw bitstreams over the physical medium?
A) Data Link
B) Network
C) Transport
D) Physical
Correct Answer: Physical
Rationale: The Physical layer, Layer 1, transmits raw bitstreams over the physical
medium and defines electrical, mechanical, and procedural specifications. The Data Link
layer handles framing, the Network layer handles routing, and the Transport layer provides
end-to-end delivery.
6. What does the Transport layer primarily provide in the OSI model?
A) Logical addressing
B) End-to-end delivery and error recovery
C) Physical transmission
D) Data formatting
Correct Answer: End-to-end delivery and error recovery
Rationale: The Transport layer, Layer 4, provides end-to-end delivery, flow control, error
recovery, segmentation, and reassembly. Logical addressing is handled by the Network
layer, physical transmission by the Physical layer, and data formatting by the Presentation
layer.
7. Which OSI layer interfaces directly with software applications?
