Question 1mediummulti select
Full question →mediummulti selectObjective-mapped
Which two statements about ARP on an IPv4 Ethernet network are correct? (Choose two.)
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
An ARP request is sent as a Layer 2 broadcast.
Correct. The requester does not yet know the destination MAC.
B
Best answer
An ARP reply is normally sent as a unicast frame.
Correct. The responder knows the requester MAC from the request.
C
Distractor review
ARP is used to map IPv6 addresses to MAC addresses.
IPv6 uses Neighbor Discovery instead of ARP.
D
Distractor review
ARP is forwarded by routers across subnets by default.
ARP is a local-segment protocol and is not routed.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is believing that ARP requests are sent as unicast frames or that ARP can resolve addresses across different subnets. Some candidates mistakenly think ARP is used for IPv6 address resolution, confusing it with Neighbor Discovery Protocol (NDP). Another common mistake is assuming routers forward ARP requests between subnets, which they do not. These misconceptions can lead to incorrect answers, as ARP strictly operates as a local broadcast mechanism for IPv4 address-to-MAC resolution within the same subnet only.
Technical deep dive
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
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?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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