WGU D413 OBJECTIVE ASSESSMENT FINAL EXAM /
TELECOMMUNICATION D413 WGU OA FINAL EXAM
2026/2027
TESTBANK COMPLETE ACCURATE EXAM ACTUAL
QUESTIONS AND CORRECT DETAILED ANSWERS WITH
RATIONALES (100% CORRECT VERIFIED SOLUTIONS)
CURRENTLY UPDATED
VERSION 2026 EDITION | GUARANTEED SUCCESS A+ | JUST
RELEASED | INSTANT DOWNLOAD
1. Which layer of the OSI model is responsible for end-to-end error
recovery and flow control?
A) Physical layer
B) Data link layer
C) Transport layer
D) Application layer
Correct Answer: C) Transport layer
Rationale: The Transport layer (Layer 4) provides reliable data transfer,
error recovery, segmentation, and flow control between hosts. TCP
operates at this layer to ensure end-to-end communication reliability.
2. The TCP/IP model combines which OSI layers into a single
"Application layer"?
A) Session, presentation, application
,B) Physical, data link, network
C) Network, transport, session
D) Data link, physical, application
Correct Answer: A) Session, presentation, application
Rationale: The TCP/IP Application layer corresponds to OSI Layers 5
(Session), 6 (Presentation), and 7 (Application), combining these
functions into a single layer for simplified protocol design.
3. Which protocol operates at the transport layer of the TCP/IP
model and provides unreliable, connectionless communication?
A) TCP
B) UDP
C) IP
D) HTTP
Correct Answer: B) UDP
Rationale: UDP (User Datagram Protocol) is connectionless and does
not guarantee delivery, ordering, or error checking. It is used for
applications where speed is prioritized over reliability, such as streaming
media and DNS.
4. The Internet Protocol (IP) operates at which OSI layer?
A) Physical
B) Data link
,C) Network
D) Transport
Correct Answer: C) Network
Rationale: IP is a Network layer (Layer 3) protocol responsible for
logical addressing and routing packets between networks. Routers
operate at this layer using IP addresses to make forwarding decisions.
5. Ethernet operates at which two OSI layers?
A) Physical and Data link
B) Network and Transport
C) Session and Presentation
D) Application and Physical
Correct Answer: A) Physical and Data link
Rationale: Ethernet covers the Physical layer (signaling, cabling) and
the Data Link layer (MAC addressing, framing, error detection). IEEE
802.3 defines these Ethernet specifications.
6. What is the primary purpose of a subnet mask?
A) Encrypt data transmission
B) Define which portion of an IP address is the network and which is the
host
C) Assign MAC addresses to devices
, D) Monitor network traffic patterns
Correct Answer: B) 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, enabling proper routing and subnetting. This allows networks
to be organized efficiently and determines which devices are on the
same local network.
7. At which layer of the OSI model does a network switch primarily
operate when forwarding frames based on MAC addresses?
A) Physical Layer
B) Data Link Layer
Answer: B) Data Link Layer
Rationale: A standard Ethernet switch operates primarily at the Data
Link layer (Layer 2) of the OSI model. It forwards Ethernet frames by
examining MAC addresses and using its MAC address table to send
frames only to the appropriate port. (Some multilayer switches can also
operate at Layer 3, but basic switching is a Layer 2 function.)
8.Which device forwards packets between different networks using
IP addresses?
A) Router
B) Hub
C) Repeater
D) Bridge
TELECOMMUNICATION D413 WGU OA FINAL EXAM
2026/2027
TESTBANK COMPLETE ACCURATE EXAM ACTUAL
QUESTIONS AND CORRECT DETAILED ANSWERS WITH
RATIONALES (100% CORRECT VERIFIED SOLUTIONS)
CURRENTLY UPDATED
VERSION 2026 EDITION | GUARANTEED SUCCESS A+ | JUST
RELEASED | INSTANT DOWNLOAD
1. Which layer of the OSI model is responsible for end-to-end error
recovery and flow control?
A) Physical layer
B) Data link layer
C) Transport layer
D) Application layer
Correct Answer: C) Transport layer
Rationale: The Transport layer (Layer 4) provides reliable data transfer,
error recovery, segmentation, and flow control between hosts. TCP
operates at this layer to ensure end-to-end communication reliability.
2. The TCP/IP model combines which OSI layers into a single
"Application layer"?
A) Session, presentation, application
,B) Physical, data link, network
C) Network, transport, session
D) Data link, physical, application
Correct Answer: A) Session, presentation, application
Rationale: The TCP/IP Application layer corresponds to OSI Layers 5
(Session), 6 (Presentation), and 7 (Application), combining these
functions into a single layer for simplified protocol design.
3. Which protocol operates at the transport layer of the TCP/IP
model and provides unreliable, connectionless communication?
A) TCP
B) UDP
C) IP
D) HTTP
Correct Answer: B) UDP
Rationale: UDP (User Datagram Protocol) is connectionless and does
not guarantee delivery, ordering, or error checking. It is used for
applications where speed is prioritized over reliability, such as streaming
media and DNS.
4. The Internet Protocol (IP) operates at which OSI layer?
A) Physical
B) Data link
,C) Network
D) Transport
Correct Answer: C) Network
Rationale: IP is a Network layer (Layer 3) protocol responsible for
logical addressing and routing packets between networks. Routers
operate at this layer using IP addresses to make forwarding decisions.
5. Ethernet operates at which two OSI layers?
A) Physical and Data link
B) Network and Transport
C) Session and Presentation
D) Application and Physical
Correct Answer: A) Physical and Data link
Rationale: Ethernet covers the Physical layer (signaling, cabling) and
the Data Link layer (MAC addressing, framing, error detection). IEEE
802.3 defines these Ethernet specifications.
6. What is the primary purpose of a subnet mask?
A) Encrypt data transmission
B) Define which portion of an IP address is the network and which is the
host
C) Assign MAC addresses to devices
, D) Monitor network traffic patterns
Correct Answer: B) 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, enabling proper routing and subnetting. This allows networks
to be organized efficiently and determines which devices are on the
same local network.
7. At which layer of the OSI model does a network switch primarily
operate when forwarding frames based on MAC addresses?
A) Physical Layer
B) Data Link Layer
Answer: B) Data Link Layer
Rationale: A standard Ethernet switch operates primarily at the Data
Link layer (Layer 2) of the OSI model. It forwards Ethernet frames by
examining MAC addresses and using its MAC address table to send
frames only to the appropriate port. (Some multilayer switches can also
operate at Layer 3, but basic switching is a Layer 2 function.)
8.Which device forwards packets between different networks using
IP addresses?
A) Router
B) Hub
C) Repeater
D) Bridge
