WGU D413 Telecommunication &
Wireless Communication Objective
Assessment Prep 2025/2026:
Business Data Communications and
Networking, 15th Edition by Jerry
FitzGerald, Alan Dennis, and
Alexandra Durcikova
PART 1: NETWORKING FUNDAMENTALS & OSI MODEL (Questions 1-25)
OSI Model Layers & Functions
Q1. Which OSI layer is responsible for reliable data delivery, error
detection, and retransmission?
A) Network (Layer 3)
B) Transport (Layer 4)
C) Data Link (Layer 2)
D) Session (Layer 5)
,,,,,answer,,,: B
Rationale: The Transport layer (Layer 4) manages error detection,
retransmission, flow control, and segmentation. TCP operates at this
,layer to ensure reliable delivery. Reliability is not handled at the Network
or Data Link layers .
Q2. At which layer of the OSI model does a switch primarily operate
when forwarding frames based on MAC addresses?
A) Physical (Layer 1)
B) Data Link (Layer 2)
C) Network (Layer 3)
D) Transport (Layer 4)
,,,,,answer,,,: B
Rationale: Switches operate at Layer 2 (Data Link) because they make
forwarding decisions based on MAC addresses. Hubs operate at Layer 1,
and routers operate at Layer 3 .
Q3. Which OSI layer is responsible for establishing, managing, and
terminating sessions between applications?
A) Transport (Layer 4)
B) Session (Layer 5)
C) Presentation (Layer 6)
D) Application (Layer 7)
,,,,,answer,,,: B
,Rationale: The Session layer (Layer 5) sets up, coordinates, and
terminates conversations, exchanges, and dialogues between
applications at each end. It manages session checkpoints and recovery .
Q4. Which layer of the OSI model interfaces directly with application
processes and provides services like email and file transfer?
A) Transport (Layer 4)
B) Session (Layer 5)
C) Presentation (Layer 6)
D) Application (Layer 7)
,,,,,answer,,,: D
Rationale: The Application layer (Layer 7) interfaces directly with
application processes and performs common application services. HTTP,
FTP, SMTP, and DNS operate at this layer .
Q5. Which OSI layer is responsible for the physical transmission of raw
bit streams over a medium?
A) Data Link (Layer 2)
B) Physical (Layer 1)
C) Network (Layer 3)
D) Transport (Layer 4)
,,,,,answer,,,: B
, Rationale: The Physical layer (Layer 1) defines electrical, mechanical, and
procedural specifications for transmitting raw bits over a physical
medium. This includes voltage levels, pin layouts, and transmission
rates .
Network Devices & Functions
Q6. Which device separates collision domains but not broadcast
domains?
A) Hub
B) Repeater
C) Switch
D) Router
,,,,,answer,,,: C
Rationale: Switches create separate collision domains per port,
improving performance by reducing collisions. However, all ports on a
switch belong to the same broadcast domain unless Virtual LANs (VLANs)
are configured .
Q7. Which device connects different networks together and routes data
between them?
A) Switch
B) Hub
Wireless Communication Objective
Assessment Prep 2025/2026:
Business Data Communications and
Networking, 15th Edition by Jerry
FitzGerald, Alan Dennis, and
Alexandra Durcikova
PART 1: NETWORKING FUNDAMENTALS & OSI MODEL (Questions 1-25)
OSI Model Layers & Functions
Q1. Which OSI layer is responsible for reliable data delivery, error
detection, and retransmission?
A) Network (Layer 3)
B) Transport (Layer 4)
C) Data Link (Layer 2)
D) Session (Layer 5)
,,,,,answer,,,: B
Rationale: The Transport layer (Layer 4) manages error detection,
retransmission, flow control, and segmentation. TCP operates at this
,layer to ensure reliable delivery. Reliability is not handled at the Network
or Data Link layers .
Q2. At which layer of the OSI model does a switch primarily operate
when forwarding frames based on MAC addresses?
A) Physical (Layer 1)
B) Data Link (Layer 2)
C) Network (Layer 3)
D) Transport (Layer 4)
,,,,,answer,,,: B
Rationale: Switches operate at Layer 2 (Data Link) because they make
forwarding decisions based on MAC addresses. Hubs operate at Layer 1,
and routers operate at Layer 3 .
Q3. Which OSI layer is responsible for establishing, managing, and
terminating sessions between applications?
A) Transport (Layer 4)
B) Session (Layer 5)
C) Presentation (Layer 6)
D) Application (Layer 7)
,,,,,answer,,,: B
,Rationale: The Session layer (Layer 5) sets up, coordinates, and
terminates conversations, exchanges, and dialogues between
applications at each end. It manages session checkpoints and recovery .
Q4. Which layer of the OSI model interfaces directly with application
processes and provides services like email and file transfer?
A) Transport (Layer 4)
B) Session (Layer 5)
C) Presentation (Layer 6)
D) Application (Layer 7)
,,,,,answer,,,: D
Rationale: The Application layer (Layer 7) interfaces directly with
application processes and performs common application services. HTTP,
FTP, SMTP, and DNS operate at this layer .
Q5. Which OSI layer is responsible for the physical transmission of raw
bit streams over a medium?
A) Data Link (Layer 2)
B) Physical (Layer 1)
C) Network (Layer 3)
D) Transport (Layer 4)
,,,,,answer,,,: B
, Rationale: The Physical layer (Layer 1) defines electrical, mechanical, and
procedural specifications for transmitting raw bits over a physical
medium. This includes voltage levels, pin layouts, and transmission
rates .
Network Devices & Functions
Q6. Which device separates collision domains but not broadcast
domains?
A) Hub
B) Repeater
C) Switch
D) Router
,,,,,answer,,,: C
Rationale: Switches create separate collision domains per port,
improving performance by reducing collisions. However, all ports on a
switch belong to the same broadcast domain unless Virtual LANs (VLANs)
are configured .
Q7. Which device connects different networks together and routes data
between them?
A) Switch
B) Hub
