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
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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 a connectionless transport-
layer protocol that does not guarantee delivery, sequencing, or
retransmission. It is commonly used where low latency is more
important than reliability, such as streaming media, VoIP, online
gaming, and DNS queries.
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 operates at both the Physical layer (signaling,
cables, connectors, and transmission) and the Data Link layer (framing,
MAC addressing, media access control, and error detection). The IEEE
802.3 standard defines 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: A subnet mask identifies the network and host portions of
an IP address. This enables proper routing, subnetting, and determines
whether 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
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 a connectionless transport-
layer protocol that does not guarantee delivery, sequencing, or
retransmission. It is commonly used where low latency is more
important than reliability, such as streaming media, VoIP, online
gaming, and DNS queries.
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 operates at both the Physical layer (signaling,
cables, connectors, and transmission) and the Data Link layer (framing,
MAC addressing, media access control, and error detection). The IEEE
802.3 standard defines 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: A subnet mask identifies the network and host portions of
an IP address. This enables proper routing, subnetting, and determines
whether 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
