N10-009 Networking Concepts Practice Question
Which of the following is a characteristic of a Layer 2 broadcast domain?
⚠ Common exam trap
Many exam-takers confuse a broadcast domain with a collision domain, or incorrectly assume that being on the same IP subnet is a requirement for receiving broadcasts, when in fact Layer 2 broadcasts are forwarded regardless of IP addressing.
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
✓
Broadcast frames are forwarded to all ports within the domain.
A Layer 2 broadcast domain consists of all devices that receive a broadcast frame sent by any device within that domain. Switches forward broadcast frames (destination MAC FF:FF:FF:FF:FF:FF) out all ports except the ingress port, ensuring every device in the same VLAN or collision-free segment sees the broadcast. This is why option C is correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Devices can communicate using MAC addresses alone.
Why it's wrong here
While devices within the same Layer 2 broadcast domain do indeed communicate using MAC addresses for direct peer-to-peer frame delivery, this capability is a fundamental aspect of any Layer 2 network segment. It is not the *defining* characteristic that specifically describes a broadcast domain. The defining characteristic of a broadcast domain relates to how broadcast frames are propagated, not simply the use of MAC addresses for unicast communication.
When this WOULD be correct
This option would be correct for a question like: 'Which of the following is true about communication within a single VLAN?' In that context, devices in the same VLAN can communicate using MAC addresses alone without needing Layer 3 routing.
- ✗
All devices must be on the same IP subnet.
Why it's wrong here
A Layer 2 broadcast domain is defined by the scope of broadcast frame propagation, which is a function of switches and VLANs, not IP addressing. While it is common and best practice to align Layer 2 broadcast domains with Layer 3 IP subnets for efficient routing and network management, it is not a technical requirement for devices to be on the same IP subnet to exist within the same broadcast domain. Misconfigurations could lead to devices in the same broadcast domain having different IP subnets, though this would hinder Layer 3 communication.
When this WOULD be correct
This option would be correct for a question like: 'Which of the following is a characteristic of devices in the same IP subnet?' In that context, all devices must be on the same IP subnet to communicate without a router.
- ✓
Broadcast frames are forwarded to all ports within the domain.
Why this is correct
The key characteristic of a broadcast domain is that a broadcast frame sent by any device is received by all other devices in that domain. Switches forward broadcasts to all ports in the same VLAN.
- ✗
Routers are required to communicate between devices in the same domain.
Why it's wrong here
Routers operate at Layer 3 and are designed to forward traffic between different IP subnets, which typically correspond to distinct broadcast domains. Within a single Layer 2 broadcast domain, devices communicate directly via MAC addresses, and switches handle the forwarding of frames to all relevant ports without needing any Layer 3 routing functionality. Therefore, routers are not involved in facilitating communication *within* the same broadcast domain, only between them.
When this WOULD be correct
In a question asking about communication between different broadcast domains (i.e., different subnets), routers are required to forward traffic between them, making this statement correct.
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.
✓Broadcast frames are forwarded to all ports within the domain.Correct answer▾
Why this is correct
The key characteristic of a broadcast domain is that a broadcast frame sent by any device is received by all other devices in that domain. Switches forward broadcasts to all ports in the same VLAN.
✗Devices can communicate using MAC addresses alone.Wrong answer — click to see why▾
Why this is wrong here
In a Layer 2 broadcast domain, devices communicate using MAC addresses, but this is not a defining characteristic of the domain itself; it's true for any Ethernet network. The question asks for a characteristic of the broadcast domain, which is that broadcast frames are forwarded to all ports.
★ When this WOULD be the correct answer
This option would be correct for a question like: 'Which of the following is true about communication within a single VLAN?' In that context, devices in the same VLAN can communicate using MAC addresses alone without needing Layer 3 routing.
Why candidates choose this
Candidates may confuse a basic feature of Ethernet (MAC-based communication) with the specific property of a broadcast domain, or they may think that MAC-only communication is unique to broadcast domains.
✗All devices must be on the same IP subnet.Wrong answer — click to see why▾
Why this is wrong here
A Layer 2 broadcast domain is defined by the reach of broadcast frames, not by IP subnetting. Devices on the same broadcast domain can be on different IP subnets; IP subnetting is a Layer 3 concept.
★ When this WOULD be the correct answer
This option would be correct for a question like: 'Which of the following is a characteristic of devices in the same IP subnet?' In that context, all devices must be on the same IP subnet to communicate without a router.
Why candidates choose this
Candidates often confuse broadcast domains with IP subnets because in typical network designs, a broadcast domain is often contained within a single subnet, leading to the mistaken belief that they are equivalent.
✗Routers are required to communicate between devices in the same domain.Wrong answer — click to see why▾
Why this is wrong here
Routers operate at Layer 3 and are not required for communication within the same Layer 2 broadcast domain; switches or bridges handle Layer 2 forwarding.
★ When this WOULD be the correct answer
In a question asking about communication between different broadcast domains (i.e., different subnets), routers are required to forward traffic between them, making this statement correct.
Why candidates choose this
Candidates may confuse the role of routers in inter-domain communication with intra-domain communication, assuming routers are needed for any device-to-device communication.
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?”
Visual reference
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
Related to this question
Learn chapter
Common Ports and Protocols
Key term
VLAN
A VLAN (Virtual Local Area Network) is a logical grouping of network devices that behave as if they are on the same physical network segment, regardless of their actual physical location.
Key term
Broadcast domain
A broadcast domain is a network segment where any device can send a broadcast message that all other devices on that segment will receive and process.
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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.