- A
A 48-bit hardware address burned into the NIC used for Layer 2 identification
This is the definition of a MAC address. MAC addresses are 48-bit hardware addresses assigned by the manufacturer and used for identifying devices at Layer 2.
- B
A logical grouping of ports that isolates broadcast domains within a switch
Why wrong: This describes a VLAN, not a MAC address. VLANs segment broadcast domains at Layer 2, while MAC addresses are hardware identifiers.
- C
A link that carries traffic for multiple VLANs using 802.1Q tagging
Why wrong: This describes a trunk link, not a MAC address. Trunks use 802.1Q encapsulation to carry multiple VLANs.
- D
A protocol that prevents loops in a redundant switched network
Why wrong: This describes Spanning Tree Protocol (STP), not a MAC address. STP prevents loops by blocking redundant paths.
Quick Answer
The correct answer is a 48-bit hardware address burned into the NIC used for Layer 2 identification. This is correct because the Ethernet MAC address is a unique, factory-assigned identifier embedded in the network interface controller’s firmware, operating at Layer 2 of the OSI model to enable local frame delivery on a LAN segment. On the CCNA 200-301 v2 exam, this definition often appears in matching questions where you must distinguish the MAC address from terms like “frame” (the Layer 2 PDU) or “broadcast frame” (sent to FF:FF:FF:FF:FF:FF). A common trap is confusing the MAC’s burned-in address (BIA) with a software-assigned IP address; remember that MACs are physical and never change, while IPs are logical. Memory tip: think “MAC = Machine Address Chip” — it’s hard-coded at the factory, not configured by you.
CCNA Network Infrastructure and Connectivity Practice Question
This 200-301 practice question tests your understanding of network infrastructure and connectivity. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: a MAC address uniquely identifies a network interface card at Layer 2 for local frame delivery within a broadcast domain.. 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.
Match each Ethernet or switching term to its most accurate description.
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 48-bit hardware address burned into the NIC used for Layer 2 identification
A MAC address is a Layer 2 hardware identifier burned into each NIC, used for local frame delivery. A frame is the Layer 2 PDU that encapsulates data for Ethernet transmission. A switch learns MAC addresses by examining source addresses and forwards frames based on destination MACs, enabling local traffic isolation. A broadcast frame is sent to the broadcast MAC address (FF:FF:FF:FF:FF:FF) and is received by all devices within the same broadcast domain.
Key principle: A MAC address uniquely identifies a network interface card at Layer 2 for local frame delivery within a broadcast domain.
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 48-bit hardware address burned into the NIC used for Layer 2 identification
Why this is correct
This is the definition of a MAC address. MAC addresses are 48-bit hardware addresses assigned by the manufacturer and used for identifying devices at Layer 2.
Related concept
A MAC address uniquely identifies a network interface card at Layer 2 for local frame delivery within a broadcast domain.
- ✗
A logical grouping of ports that isolates broadcast domains within a switch
Why it's wrong here
This describes a VLAN, not a MAC address. VLANs segment broadcast domains at Layer 2, while MAC addresses are hardware identifiers.
- ✗
A link that carries traffic for multiple VLANs using 802.1Q tagging
Why it's wrong here
This describes a trunk link, not a MAC address. Trunks use 802.1Q encapsulation to carry multiple VLANs.
- ✗
A protocol that prevents loops in a redundant switched network
Why it's wrong here
This describes Spanning Tree Protocol (STP), not a MAC address. STP prevents loops by blocking redundant paths.
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 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓A 48-bit hardware address burned into the NIC used for Layer 2 identificationCorrect answer▾
Why this is correct
This is the definition of a MAC address. MAC addresses are 48-bit hardware addresses assigned by the manufacturer and used for identifying devices at Layer 2.
✗A logical grouping of ports that isolates broadcast domains within a switchWrong answer — click to see why▾
Why this is wrong here
The description matches VLAN functionality, not MAC addressing.
Why candidates choose this
Candidates may confuse MAC addresses with VLANs because both are Layer 2 concepts.
✗A link that carries traffic for multiple VLANs using 802.1Q taggingWrong answer — click to see why▾
Why this is wrong here
The description is for trunking, which is a different switching concept.
Why candidates choose this
Candidates might think MAC addresses are involved in trunking because frames carry MAC addresses, but the term itself is not a MAC address.
✗A protocol that prevents loops in a redundant switched networkWrong answer — click to see why▾
Why this is wrong here
The description matches STP, which is a separate protocol from MAC addressing.
Why candidates choose this
Candidates may associate MAC addresses with STP because STP uses MAC addresses in BPDUs, but the term itself is not STP.
Analysis generated from the official 200-301blueprint 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
Be careful not to confuse MAC addresses with other Layer 2 terms like VLANs, trunks, or STP. Each term has a specific definition; MAC addresses are hardware identifiers, not logical groupings or protocols.
Detailed technical explanation
How to think about this question
Ethernet and switching fundamentals revolve around the concept of Layer 2 addressing and frame forwarding. A MAC address is a unique hardware identifier assigned to each network interface card (NIC). It operates at Layer 2 of the OSI model and is essential for local network communication because switches use MAC addresses to forward frames within the same broadcast domain. A frame is the Layer 2 encapsulation unit that carries data between devices on an Ethernet network, including source and destination MAC addresses, control information, and payload data. Switches operate by learning MAC addresses from incoming frames and building a MAC address table. This table maps MAC addresses to specific switch ports, enabling the switch to forward frames only to the intended recipient port rather than flooding all ports. This selective forwarding improves network efficiency and security. Broadcast traffic, however, is an exception; it is sent to all devices within the broadcast domain because the destination MAC address is a broadcast address (FF:FF:FF:FF:FF:FF). Broadcasts are used for essential network functions like ARP requests and DHCP discovery. A common confusion arises when differentiating between unicast, multicast, and broadcast traffic and the role of switches in forwarding these frames. Switches forward unicast frames based on MAC address tables but flood unknown unicast and broadcast frames to all ports except the source. Understanding this behavior is crucial for troubleshooting and designing VLANs, as broadcast domains are segmented by routers or layer 3 switches to limit broadcast traffic. Cisco switches implement these rules consistently, making mastery of these concepts vital for the CCNA exam and real-world networking.
KKey Concepts to Remember
- A MAC address uniquely identifies a network interface card at Layer 2 for local frame delivery within a broadcast domain.
- A frame is the Layer 2 data unit on Ethernet that encapsulates payload with source and destination MAC addresses and control information.
- A switch learns MAC addresses from incoming frames and builds a MAC address table to forward frames selectively to the correct port.
- Switches forward unicast frames based on MAC address tables but flood broadcast frames to all ports within the broadcast domain.
- Broadcast traffic uses a special MAC address and is sent to all devices in the broadcast domain to support essential network services.
- Switches do not forward broadcast frames outside their broadcast domain, which is typically segmented by routers or VLAN boundaries.
- Unknown unicast frames are flooded by switches because the destination MAC address is not in the MAC address table.
- Understanding the difference between MAC addresses, frames, switches, and broadcast traffic is essential for troubleshooting and designing switched networks.
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
A MAC address uniquely identifies a network interface card at Layer 2 for local frame delivery within a broadcast domain.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
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Review a MAC address uniquely identifies a network interface card at Layer 2 for local frame delivery within a broadcast domain., then practise related 200-301 questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this 200-301 question test?
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — A MAC address uniquely identifies a network interface card at Layer 2 for local frame delivery within a broadcast domain..
What is the correct answer to this question?
The correct answer is: A 48-bit hardware address burned into the NIC used for Layer 2 identification — A MAC address is a Layer 2 hardware identifier burned into each NIC, used for local frame delivery. A frame is the Layer 2 PDU that encapsulates data for Ethernet transmission. A switch learns MAC addresses by examining source addresses and forwards frames based on destination MACs, enabling local traffic isolation. A broadcast frame is sent to the broadcast MAC address (FF:FF:FF:FF:FF:FF) and is received by all devices within the same broadcast domain.
What should I do if I get this 200-301 question wrong?
Review a MAC address uniquely identifies a network interface card at Layer 2 for local frame delivery within a broadcast domain., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
A MAC address uniquely identifies a network interface card at Layer 2 for local frame delivery within a broadcast domain.
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Last reviewed: May 17, 2026
This 200-301 practice question is part of Courseiva's free Cisco 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 200-301 exam.
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