N10-009 Networking Concepts Practice Question
Which transport layer protocol is used by VoIP and streaming video because it provides low latency and does not require retransmission?
⚠ Common exam trap
CompTIA often tests the misconception that 'reliable delivery is always better,' leading candidates to choose TCP, but the trap is that real-time applications prioritize low latency over guaranteed delivery, making UDP the correct choice.
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
VoIP and streaming video use UDP (User Datagram Protocol) because it is connectionless and provides low-latency transmission without retransmission of lost packets. This is critical for real-time applications where a slight delay is more disruptive than occasional packet loss.
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
Why it's wrong here
Transmission Control Protocol (TCP) is a connection-oriented transport layer protocol that guarantees reliable, ordered, and error-checked delivery of data. It achieves this through mechanisms like sequence numbers, acknowledgments, retransmissions of lost packets, flow control, and congestion control. While essential for applications requiring data integrity, these reliability features introduce significant overhead and latency, making TCP unsuitable for real-time applications such as VoIP and video streaming where timely delivery is paramount over perfect data integrity.
When this WOULD be correct
For a question asking which transport layer protocol ensures reliable, ordered delivery of data (e.g., for file transfers, web pages, or email), TCP would be the correct answer because it guarantees retransmission and error checking.
- ✓
UDP
Why this is correct
User Datagram Protocol (UDP) is a connectionless transport layer protocol that prioritizes speed and low latency over guaranteed delivery. It does not establish a session, perform error checking, or retransmit lost packets, which significantly reduces overhead. This makes UDP ideal for real-time applications like Voice over IP (VoIP) and video streaming, where occasional packet loss is preferable to the delays introduced by retransmission and flow control mechanisms. The continuous flow of media data benefits from UDP's minimal processing requirements.
- ✗
ICMP
Why it's wrong here
The Internet Control Message Protocol (ICMP) operates at the network layer and is primarily used for diagnostic, error-reporting, and control functions within the IP network. It is not designed to transport application-layer data for end-user services. Examples include reporting unreachable hosts, time exceeded messages, and echo requests/replies used by utilities like `ping` and `traceroute` to troubleshoot network connectivity and performance issues.
When this WOULD be correct
ICMP would be correct for a question asking: 'Which protocol is used by the ping command to test network connectivity and report errors?' or 'Which protocol is used by routers to send error messages about unreachable destinations?'
- ✗
IGMP
Why it's wrong here
The Internet Group Management Protocol (IGMP) operates at the network layer and is specifically designed for managing multicast group memberships. It allows hosts to inform local routers that they wish to receive multicast traffic for a particular group, but it does not transport application data itself. IGMP facilitates efficient one-to-many communication by enabling routers to forward multicast streams only to segments where active group members reside, rather than being a protocol for direct data delivery.
When this WOULD be correct
A question asking: 'Which protocol is used by a host to join a multicast group to receive streaming video?' would have IGMP as the correct answer, as it manages group membership for multicast traffic.
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
User Datagram Protocol (UDP) is a connectionless transport layer protocol that prioritizes speed and low latency over guaranteed delivery. It does not establish a session, perform error checking, or retransmit lost packets, which significantly reduces overhead. This makes UDP ideal for real-time applications like Voice over IP (VoIP) and video streaming, where occasional packet loss is preferable to the delays introduced by retransmission and flow control mechanisms. The continuous flow of media data benefits from UDP's minimal processing requirements.
✗TCPWrong answer — click to see why▾
Why this is wrong here
TCP provides reliable, connection-oriented delivery with retransmission of lost packets, which increases latency and is unsuitable for real-time applications like VoIP and streaming video that prioritize low latency over reliability.
★ When this WOULD be the correct answer
For a question asking which transport layer protocol ensures reliable, ordered delivery of data (e.g., for file transfers, web pages, or email), TCP would be the correct answer because it guarantees retransmission and error checking.
Why candidates choose this
Candidates may associate TCP with all internet traffic due to its prevalence in HTTP, FTP, and email, overlooking that real-time media requires a protocol with lower overhead and no retransmission delays.
✗ICMPWrong answer — click to see why▾
Why this is wrong here
ICMP is a network layer protocol used for error reporting and diagnostics (e.g., ping), not for transporting VoIP or streaming video data. It does not provide the low-latency, connectionless transport required for real-time media.
★ When this WOULD be the correct answer
ICMP would be correct for a question asking: 'Which protocol is used by the ping command to test network connectivity and report errors?' or 'Which protocol is used by routers to send error messages about unreachable destinations?'
Why candidates choose this
Candidates may confuse ICMP with UDP because both are connectionless and used in network diagnostics, but ICMP is not a transport layer protocol and does not carry application data like VoIP.
✗IGMPWrong answer — click to see why▾
Why this is wrong here
IGMP (Internet Group Management Protocol) is used for managing multicast group memberships, not for transporting VoIP or streaming video data. It operates at the network layer, not the transport layer, and does not handle low-latency data delivery or retransmission.
★ When this WOULD be the correct answer
A question asking: 'Which protocol is used by a host to join a multicast group to receive streaming video?' would have IGMP as the correct answer, as it manages group membership for multicast traffic.
Why candidates choose this
Candidates may confuse IGMP with UDP because both are associated with multicast streaming, but IGMP is for group management, not data transport.
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?”
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 |
Go deeper
Related to this question
Learn chapter
TCP/IP Model and Protocol Suite
Key term
Packet
A packet is a small unit of data that is sent over a network, containing both the actual data and control information for delivery.
Key term
Packet loss
Packet loss is the failure of one or more data packets to reach their destination across a network, resulting in missing or incomplete data transfers.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.