- A
TCP
Why wrong: TCP is connection-oriented; it uses a three-way handshake to establish a session before data transfer.
- B
UDP
UDP is a connectionless protocol; it sends data without establishing a connection, making it faster but less reliable.
- C
ICMP
Why wrong: ICMP is a network-layer protocol used for diagnostics (e.g., ping), not a transport-layer protocol.
- D
ARP
Why wrong: ARP is a data-link layer protocol used to resolve IP addresses to MAC addresses; it does not operate at the transport layer.
Question 75 of 520
UDP: A Connectionless Protocol at the Transport Layer
This N10-009 practice question tests your understanding of networking concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network technician is explaining the difference between connection-oriented and connectionless protocols to a junior technician. Which of the following protocols is connectionless at the transport layer?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
UDP
UDP (User Datagram Protocol) is the correct answer because it is a connectionless transport-layer protocol. It does not establish a session or guarantee delivery, instead sending datagrams independently without handshaking or acknowledgments, which makes it suitable for real-time applications like VoIP and streaming.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
TCP
- ✓
UDP
Why this is correct
UDP is a connectionless protocol; it sends data without establishing a connection, making it faster but less reliable.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
ICMP
- ✗
ARP
Why it's wrong here
ARP is a data-link layer protocol used to resolve IP addresses to MAC addresses; it does not operate at the transport layer.
When this WOULD be correct
A question asking which protocol is used to map an IP address to a MAC address on a local network, or which protocol operates at Layer 2 and is essential for Ethernet communication.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓UDPCorrect answer▾
Why this is correct
UDP is a connectionless protocol; it sends data without establishing a connection, making it faster but less reliable.
✗TCPWrong answer — click to see why▾
Why this is wrong here
TCP is a connection-oriented protocol at the transport layer, meaning it establishes a reliable connection before data transfer, which is the opposite of connectionless.
★ When this WOULD be the correct answer
If the question asked 'Which of the following is a connection-oriented protocol at the transport layer?', then TCP would be the correct answer.
Why candidates choose this
Candidates may confuse TCP with UDP due to both operating at the transport layer, or they might think TCP's reliability implies it is connectionless because it can handle packet loss.
✗ICMPWrong answer — click to see why▾
Why this is wrong here
ICMP operates at the network layer (Layer 3), not the transport layer. The question specifically asks for a connectionless protocol at the transport layer, which is UDP.
★ When this WOULD be the correct answer
A question asking 'Which protocol is used for error reporting and diagnostic functions at the network layer?' would make ICMP the correct answer.
Why candidates choose this
Candidates may confuse ICMP as connectionless because it does not establish a connection before sending messages, but they overlook that it belongs to the network layer, not the transport layer.
✗ARPWrong answer — click to see why▾
Why this is wrong here
ARP operates at the Data Link layer (Layer 2) and resolves IP addresses to MAC addresses; it is not a transport layer protocol and does not provide connectionless transport services.
★ When this WOULD be the correct answer
A question asking which protocol is used to map an IP address to a MAC address on a local network, or which protocol operates at Layer 2 and is essential for Ethernet communication.
Why candidates choose this
Candidates may confuse ARP's lack of connection establishment with connectionless transport, or mistakenly think ARP operates at the transport layer because it works with IP addresses.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse ICMP or ARP as transport-layer protocols because they are involved in network communication, but the question specifically asks for the transport layer, where only TCP and UDP reside, and UDP is the connectionless one.
Detailed technical explanation
How to think about this question
UDP uses a minimal 8-byte header with source/destination ports, length, and checksum, and relies on application-layer logic for reliability if needed. In real-world scenarios, DNS queries use UDP by default (port 53) to reduce latency, falling back to TCP only when responses exceed 512 bytes or for zone transfers. The connectionless nature means no sequence numbers or flow control, so packet loss is handled by the application, as seen in real-time video streaming where a lost frame is preferable to retransmission delays.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the N10-009 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
What to study next
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FAQ
Questions learners often ask
What does this N10-009 question test?
Networking Concepts — This question tests Networking Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: UDP — UDP (User Datagram Protocol) is the correct answer because it is a connectionless transport-layer protocol. It does not establish a session or guarantee delivery, instead sending datagrams independently without handshaking or acknowledgments, which makes it suitable for real-time applications like VoIP and streaming.
What should I do if I get this N10-009 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on N10-009
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which of the following is a characteristic of UDP when compared to TCP?
medium- A.A) UDP uses sequence numbers for ordering
- B.B) UDP provides reliable data delivery
- ✓ C.C) UDP has lower overhead due to minimal header
- D.D) UDP requires a three-way handshake to establish a connection
Why C: UDP (User Datagram Protocol) has a minimal 8-byte header compared to TCP's 20-byte header, resulting in lower overhead and faster transmission. Unlike TCP, UDP does not provide reliability, flow control, or error recovery, making it ideal for real-time applications like VoIP or video streaming where speed is prioritized over guaranteed delivery.
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Last reviewed: Jun 11, 2026
This N10-009 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the N10-009 exam.
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