The answer is that an ARP reply is normally sent as a unicast frame, while an ARP request is broadcast. This is correct because ARP operation on an IPv4 Ethernet network relies on the Address Resolution Protocol to map a known IPv4 address to an unknown MAC address; the requesting host sends a broadcast frame to reach every device on the local segment, but only the target device responds directly to the requester’s MAC address using a unicast reply. On the CCNA 200-301 v2 exam, this concept tests your understanding of Layer 2 and Layer 3 interaction, often appearing in questions about frame forwarding or troubleshooting connectivity—a common trap is assuming the reply is also broadcast, which would flood the network unnecessarily. Remember the memory tip: “Request shouts, reply whispers”—the request is a broadcast shout to all, but the reply is a quiet unicast whisper back to the asker.
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: aRP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC.. 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.
Which two statements about ARP on an IPv4 Ethernet network are correct? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
An ARP request is sent as a Layer 2 broadcast.
ARP resolves an IPv4 address to a MAC address on the local segment. ARP requests are broadcast; ARP replies are typically unicast.
Key principle: ARP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
An ARP request is sent as a Layer 2 broadcast.
Why this is correct
Correct. The requester does not yet know the destination MAC.
Related concept
ARP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC.
✓
An ARP reply is normally sent as a unicast frame.
Why this is correct
Correct. The responder knows the requester MAC from the request.
Related concept
ARP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC.
✗
ARP is used to map IPv6 addresses to MAC addresses.
In a question focused on IPv6 networking, where the task is to identify protocols that map addresses, an option stating that ARP maps IPv6 addresses to MAC addresses could be correct if it was framed in the context of discussing legacy support or compatibility considerations in mixed environments.
✗
ARP is forwarded by routers across subnets by default.
Why it's wrong here
ARP is a local-segment protocol and is not routed.
When this WOULD be correct
If the question were to ask about protocols that can be forwarded by routers, such as ICMP or routing protocols, then this option could be correct in the context of discussing how certain network protocols behave across subnets.
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.
✓An ARP request is sent as a Layer 2 broadcast.Correct answer▾
Why this is correct
Correct. The requester does not yet know the destination MAC.
✗ARP is used to map IPv6 addresses to MAC addresses.Wrong answer — click to see why▾
Why this is wrong here
ARP is specifically designed for IPv4 networks to map IPv4 addresses to MAC addresses. IPv6 uses Neighbor Discovery Protocol (NDP) with ICMPv6 messages to perform address resolution, not ARP.
★ When this WOULD be the correct answer
In a question focused on IPv6 networking, where the task is to identify protocols that map addresses, an option stating that ARP maps IPv6 addresses to MAC addresses could be correct if it was framed in the context of discussing legacy support or compatibility considerations in mixed environments.
Why candidates choose this
Students may confuse ARP with a general address resolution protocol and assume it works for both IPv4 and IPv6, especially since both involve mapping network-layer addresses to data-link layer addresses.
✗ARP is forwarded by routers across subnets by default.Wrong answer — click to see why▾
Why this is wrong here
ARP operates only within a single broadcast domain (subnet) and is not forwarded by routers. Routers separate broadcast domains and do not forward ARP requests or replies across subnets by default.
★ When this WOULD be the correct answer
If the question were to ask about protocols that can be forwarded by routers, such as ICMP or routing protocols, then this option could be correct in the context of discussing how certain network protocols behave across subnets.
Why candidates choose this
Test-takers might think that because routers forward IP packets, they would also forward ARP messages, not realizing that ARP is a Layer 2 protocol confined to the local network segment.
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 ARP requests with replies, and remember that ARP operates only within a local segment.
Detailed technical explanation
How to think about this question
Address Resolution Protocol (ARP) is a fundamental protocol used in IPv4 Ethernet networks to map a known IPv4 address to its corresponding MAC address. When a device wants to communicate with another device on the same local network, it must know the destination MAC address to encapsulate the packet properly at Layer 2. Since the sender only knows the IPv4 address initially, it broadcasts an ARP request frame to all devices on the local segment, asking "Who has this IPv4 address?" The device with the matching IPv4 address responds with an ARP reply containing its MAC address.
The ARP request is always sent as a Layer 2 broadcast because the sender does not yet know the MAC address of the target device. This broadcast ensures that all devices on the local Ethernet segment receive the request. The ARP reply, however, is sent as a unicast frame directly back to the requester, using the MAC address learned from the ARP request frame. This unicast reply minimizes unnecessary network traffic. Importantly, ARP operates only within the local subnet; routers do not forward ARP requests or replies across different subnets, as ARP is a link-layer protocol designed for local address resolution.
A common exam trap is confusing ARP with IPv6 address resolution protocols. IPv6 networks do not use ARP; instead, they use the Neighbor Discovery Protocol (NDP), which performs similar functions but operates differently. Another trap is assuming ARP requests can cross routers; in reality, ARP is confined to the local broadcast domain. Understanding these behaviors helps network engineers troubleshoot address resolution issues and optimize network performance in Cisco environments.
KKey Concepts to Remember
ARP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC.
An ARP request is sent as a Layer 2 broadcast because the sender does not know the MAC address of the target IPv4 address.
An ARP reply is typically sent as a unicast frame directly to the requester, using the MAC address learned from the ARP request.
ARP operates only within the local subnet and is not forwarded or routed by Layer 3 devices such as routers.
IPv6 networks do not use ARP; instead, they use the Neighbor Discovery Protocol (NDP) to resolve IPv6 addresses to MAC addresses.
Routers do not forward ARP requests across subnets because ARP is designed for local link-layer address resolution only.
A device caches ARP replies to reduce broadcast traffic and speed up future communications to the same IPv4 address.
Understanding ARP behavior is critical for troubleshooting IP-to-MAC address resolution issues in Cisco network environments.
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
ARP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review aRP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC., then practise related 200-301 questions on the same topic to reinforce the concept.
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — ARP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC..
What is the correct answer to this question?
The correct answer is: An ARP request is sent as a Layer 2 broadcast. — ARP resolves an IPv4 address to a MAC address on the local segment. ARP requests are broadcast; ARP replies are typically unicast.
What should I do if I get this 200-301 question wrong?
Review aRP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
ARP resolves IPv4 addresses to MAC addresses by broadcasting a Layer 2 request on the local Ethernet segment to discover the destination MAC.
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