N10-009 Networking Concepts Practice Question
In a network, a collision domain is a network segment where which of the following is true?
⚠ Common exam trap
Test-takers frequently confuse collision domains with broadcast domains, mistakenly thinking that confining broadcast traffic or sharing an IP subnet defines a collision domain, when in fact collision domains are strictly about physical-layer contention for the medium.
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
✓
A: Only one device can transmit at a time to avoid data collisions
In a collision domain, only one device can transmit at a time because if two or more devices transmit simultaneously, their signals collide, corrupting the data. This is a fundamental characteristic of half-duplex Ethernet segments, such as those using hubs or legacy bus topologies, where the medium is shared and CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is used to manage access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A: Only one device can transmit at a time to avoid data collisions
Why this is correct
A collision domain is a network segment where all connected devices share the same physical medium, such as an Ethernet hub or a shared coaxial cable. In such an environment, only one device can successfully transmit data at any given moment. If two or more devices attempt to transmit simultaneously, their signals interfere, resulting in a data collision that corrupts the frames and necessitates retransmission. This fundamental limitation defines the boundaries of a collision domain.
- ✗
B: All devices share the same IP subnet
Why it's wrong here
While devices within a collision domain often share the same IP subnet, sharing an IP subnet primarily defines a broadcast domain, not a collision domain. A broadcast domain encompasses all devices that receive a broadcast frame sent by any device within that segment, typically bounded by routers. Collision domains, conversely, are concerned with the physical medium and the potential for simultaneous data transmission interference, which is a much lower-level concept than IP addressing.
When this WOULD be correct
This option would be correct for a question asking: 'What is a characteristic of devices in the same broadcast domain?' or 'In a VLAN, which of the following is true?' where all devices share the same IP subnet.
- ✗
C: Broadcast traffic is confined to that segment
Why it's wrong here
The confinement of broadcast traffic to a specific network segment accurately describes a broadcast domain, which is a logical division of a computer network where all nodes can reach each other by broadcast at the data link layer. Routers typically serve as boundaries for broadcast domains, preventing broadcast storms from propagating across the entire network. This concept is distinct from a collision domain, which focuses on the physical layer and the potential for data signal interference on a shared medium.
When this WOULD be correct
This option would be correct for a question asking: 'In a network, a broadcast domain is a network segment where which of the following is true?'
- ✗
D: MAC addresses are resolved to IP addresses
Why it's wrong here
Resolving MAC addresses to IP addresses is the primary function of the Address Resolution Protocol (ARP), which operates at Layer 2 and Layer 3 of the OSI model. ARP facilitates communication within a local network by mapping logical IP addresses to physical MAC addresses, enabling devices to send frames to the correct destination hardware. This process is entirely distinct from the concept of a collision domain, which concerns shared physical media and simultaneous transmissions.
When this WOULD be correct
This option would be correct for a question like: 'Which protocol resolves MAC addresses to IP addresses?' or 'What is the function of ARP in a network?'
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.
✓A: Only one device can transmit at a time to avoid data collisionsCorrect answer▾
Why this is correct
A collision domain is a network segment where all connected devices share the same physical medium, such as an Ethernet hub or a shared coaxial cable. In such an environment, only one device can successfully transmit data at any given moment. If two or more devices attempt to transmit simultaneously, their signals interfere, resulting in a data collision that corrupts the frames and necessitates retransmission. This fundamental limitation defines the boundaries of a collision domain.
✗B: All devices share the same IP subnetWrong answer — click to see why▾
Why this is wrong here
A collision domain is defined by the possibility of frame collisions when multiple devices transmit simultaneously, not by IP subnet membership. Devices on different IP subnets can still be in the same collision domain if connected via a hub or repeater.
★ When this WOULD be the correct answer
This option would be correct for a question asking: 'What is a characteristic of devices in the same broadcast domain?' or 'In a VLAN, which of the following is true?' where all devices share the same IP subnet.
Why candidates choose this
Candidates often confuse collision domains with broadcast domains or VLANs, mistakenly thinking that sharing an IP subnet implies sharing a collision domain, when in fact collision domains are layer 1 constructs.
✗C: Broadcast traffic is confined to that segmentWrong answer — click to see why▾
Why this is wrong here
A collision domain is defined by the possibility of data collisions when multiple devices transmit simultaneously; broadcast confinement describes a broadcast domain, not a collision domain.
★ When this WOULD be the correct answer
This option would be correct for a question asking: 'In a network, a broadcast domain is a network segment where which of the following is true?'
Why candidates choose this
Candidates often confuse collision domains with broadcast domains because both involve segmentation, and the term 'confined' seems similar to limiting collisions.
✗D: MAC addresses are resolved to IP addressesWrong answer — click to see why▾
Why this is wrong here
In a collision domain, the key issue is data collisions from simultaneous transmissions, not MAC-to-IP resolution. MAC-to-IP resolution is performed by ARP, which is unrelated to collision domains.
★ When this WOULD be the correct answer
This option would be correct for a question like: 'Which protocol resolves MAC addresses to IP addresses?' or 'What is the function of ARP in a network?'
Why candidates choose this
Candidates may confuse collision domains with address resolution concepts, thinking that resolving addresses is necessary to avoid collisions, or they may misremember the definition of a collision domain.
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?”
Go deeper
Related to this question
Learn chapter
Network Virtualization and VXLAN
Key term
Segment
A segment is a division of a larger network, such as a collision domain, broadcast domain, or a portion of a TCP data stream, used to organize traffic and improve performance.
Key term
TX
TX (Transmit/Transmitter) is the signal path that sends data from a device to another device or network medium.
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JA
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.