WGU D413 Telecommunications & Wireless
Communications Exam Prep OA
V1 and V2 |
Questions and Answers | 2026 Update
| 100% Correct.
SECTION 1: OSI AND TCP/IP MODELS
Q1. 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
Answer: C) Transport layer
Rationale: The Transport layer (Layer 4) provides reliable data transfer, error recovery,
and flow control between end systems. It ensures complete data delivery and handles
segmentation and reassembly.
Q2. 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
Answer: A) Session, presentation, application
, Rationale: The TCP/IP Application layer corresponds to OSI Layers 5, 6, and 7 (Session,
Presentation, and Application). TCP/IP was designed to be simpler with only four layers
compared to OSI's seven.
Q3. 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
Answer: B) UDP
Rationale: UDP (User Datagram Protocol) is connectionless and does not guarantee
delivery, ordering, or error checking. It is used for streaming media, VoIP, and DNS
where speed is prioritized over reliability.
Q4. The Internet Protocol (IP) operates at which OSI layer?
A) Physical
B) Data link
C) Network
D) Transport
Answer: C) Network
Rationale: IP is a Network layer (Layer 3) protocol responsible for logical addressing and
routing packets across networks. It handles packet forwarding and addressing.
Q5. Ethernet operates at which two OSI layers?
A) Physical and Data link
, B) Network and Transport
C) Session and Presentation
D) Application and Physical
Answer: A) Physical and Data link
Rationale: Ethernet covers the Physical layer (signaling, cabling) and Data Link layer
(MAC addressing, framing, error detection) of the OSI model.
Q6. Which layer of the OSI model interfaces directly with applications and
performs common application services?
A) Transport layer
B) Session layer
C) Application layer
D) Presentation layer
Answer: C) Application layer
Rationale: The Application layer (Layer 7) interfaces directly with applications and
performs common application services. It is the top layer of the OSI model.
Q7. The Address Resolution Protocol (ARP) resolves which two address types?
A) IP addresses to domain names
B) IP addresses to MAC addresses
C) MAC addresses to IP addresses
D) Domain names to IP addresses
Answer: B) IP addresses to MAC addresses
Rationale: ARP resolves an assigned IPv4 network address to a physical MAC address. It
maps logical IP addresses to physical hardware addresses on the local network
segment.
, Q8. Which layer of the OSI model is responsible for routing and addressing?
A) Physical
B) Data link
C) Network
D) Transport
Answer: C) Network
Rationale: The Network layer (Layer 3) is responsible for routing, logical addressing, and
path determination. IP operates at this layer.
SECTION 2: NETWORK TOPOLOGIES AND CABLING
Q9. Which Ethernet classification specifies the use of RG-58 cable and a data rate
of 10 Mbps?
A) 10BaseT
B) 10Base2
C) 10Base5
D) 100BaseT
Answer: B) 10Base2
Rationale: 10Base2 specifies the use of RG-58 coaxial cable (thinnet) and operates at a
data rate of 10 Mbps. It was one of the early Ethernet standards.
Q10. What was the first IEEE 802.3 classification developed for Ethernet?
A) 10Base2
B) 10BaseT
C) 10Base5
D) 100BaseTX
Answer: C) 10Base5
Communications Exam Prep OA
V1 and V2 |
Questions and Answers | 2026 Update
| 100% Correct.
SECTION 1: OSI AND TCP/IP MODELS
Q1. 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
Answer: C) Transport layer
Rationale: The Transport layer (Layer 4) provides reliable data transfer, error recovery,
and flow control between end systems. It ensures complete data delivery and handles
segmentation and reassembly.
Q2. 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
Answer: A) Session, presentation, application
, Rationale: The TCP/IP Application layer corresponds to OSI Layers 5, 6, and 7 (Session,
Presentation, and Application). TCP/IP was designed to be simpler with only four layers
compared to OSI's seven.
Q3. 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
Answer: B) UDP
Rationale: UDP (User Datagram Protocol) is connectionless and does not guarantee
delivery, ordering, or error checking. It is used for streaming media, VoIP, and DNS
where speed is prioritized over reliability.
Q4. The Internet Protocol (IP) operates at which OSI layer?
A) Physical
B) Data link
C) Network
D) Transport
Answer: C) Network
Rationale: IP is a Network layer (Layer 3) protocol responsible for logical addressing and
routing packets across networks. It handles packet forwarding and addressing.
Q5. Ethernet operates at which two OSI layers?
A) Physical and Data link
, B) Network and Transport
C) Session and Presentation
D) Application and Physical
Answer: A) Physical and Data link
Rationale: Ethernet covers the Physical layer (signaling, cabling) and Data Link layer
(MAC addressing, framing, error detection) of the OSI model.
Q6. Which layer of the OSI model interfaces directly with applications and
performs common application services?
A) Transport layer
B) Session layer
C) Application layer
D) Presentation layer
Answer: C) Application layer
Rationale: The Application layer (Layer 7) interfaces directly with applications and
performs common application services. It is the top layer of the OSI model.
Q7. The Address Resolution Protocol (ARP) resolves which two address types?
A) IP addresses to domain names
B) IP addresses to MAC addresses
C) MAC addresses to IP addresses
D) Domain names to IP addresses
Answer: B) IP addresses to MAC addresses
Rationale: ARP resolves an assigned IPv4 network address to a physical MAC address. It
maps logical IP addresses to physical hardware addresses on the local network
segment.
, Q8. Which layer of the OSI model is responsible for routing and addressing?
A) Physical
B) Data link
C) Network
D) Transport
Answer: C) Network
Rationale: The Network layer (Layer 3) is responsible for routing, logical addressing, and
path determination. IP operates at this layer.
SECTION 2: NETWORK TOPOLOGIES AND CABLING
Q9. Which Ethernet classification specifies the use of RG-58 cable and a data rate
of 10 Mbps?
A) 10BaseT
B) 10Base2
C) 10Base5
D) 100BaseT
Answer: B) 10Base2
Rationale: 10Base2 specifies the use of RG-58 coaxial cable (thinnet) and operates at a
data rate of 10 Mbps. It was one of the early Ethernet standards.
Q10. What was the first IEEE 802.3 classification developed for Ethernet?
A) 10Base2
B) 10BaseT
C) 10Base5
D) 100BaseTX
Answer: C) 10Base5
