Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Dynamic ARP Inspection is most effective at preventing which attack?
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
Distractor review
SYN flood
DAI does not inspect TCP session setup behavior.
B
Best answer
ARP spoofing
Correct. DAI is designed to stop forged ARP information.
C
Distractor review
Route summarization error
That is a routing design issue, not an ARP attack.
D
Distractor review
Rogue DHCP relay
DAI does not function as DHCP relay control.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is mistaking Dynamic ARP Inspection as a tool to prevent attacks like SYN floods or rogue DHCP relays. Candidates may incorrectly associate DAI with TCP session protection or DHCP control because these are common network security concerns. However, DAI specifically validates ARP packets to prevent ARP spoofing and poisoning. Selecting options related to SYN floods or DHCP relay attacks ignores the Layer 2 focus of DAI and leads to incorrect answers. Understanding the exact protocol and attack vector DAI protects against is crucial to avoid this trap.
Technical deep dive
How to think about this question
Dynamic ARP Inspection (DAI) is a security feature used in Cisco networks to prevent ARP spoofing attacks by validating ARP packets on untrusted Layer 2 ports. ARP spoofing involves an attacker sending forged ARP messages to associate their MAC address with the IP address of another host, enabling man-in-the-middle attacks or denial of service. DAI intercepts ARP requests and replies, comparing them against a trusted database, typically built from DHCP snooping bindings, to ensure only valid ARP traffic is forwarded. DAI operates by inspecting ARP packets on access ports and verifying that the MAC-to-IP bindings match the entries in the DHCP snooping binding table or static entries. If an ARP packet fails validation, DAI drops it, effectively blocking forged ARP messages. This mechanism is specifically designed to prevent ARP spoofing and poisoning attacks, which are common threats in switched LAN environments. Other attacks like SYN floods or routing errors are outside DAI’s scope because they target different protocol layers or functions. A common exam trap is confusing DAI’s function with protections against other types of attacks such as SYN floods or DHCP relay attacks. While DAI secures ARP traffic, it does not inspect TCP session setups or control DHCP relay behavior. Understanding that DAI’s role is limited to ARP packet validation helps avoid selecting incorrect answers related to unrelated attack types. In practical networks, enabling DAI on access switches enhances LAN security by preventing attackers from poisoning the ARP cache and intercepting traffic.
KKey Concepts to Remember
- Dynamic ARP Inspection validates ARP packets by comparing them against trusted MAC-to-IP bindings to prevent ARP spoofing attacks on Layer 2 networks.
- DAI uses DHCP snooping binding tables to verify the legitimacy of ARP requests and replies on untrusted switch ports.
- DAI blocks forged ARP messages that could redirect traffic or enable man-in-the-middle attacks, enhancing LAN security.
- DAI does not inspect or prevent attacks related to TCP session setup, such as SYN floods, because it operates at Layer 2 focusing on ARP traffic.
- DAI is not designed to control DHCP relay behavior or prevent rogue DHCP relay attacks, which require different security mechanisms.
- Enabling DAI on access ports helps prevent ARP poisoning by dropping invalid ARP packets before they reach other hosts.
- Understanding the specific attack vectors DAI protects against helps avoid confusing it with unrelated network security features.
- DAI complements DHCP snooping by using its binding database to enforce ARP packet integrity in switched LAN 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?
Dynamic ARP Inspection validates ARP packets by comparing them against trusted MAC-to-IP bindings to prevent ARP spoofing attacks on Layer 2 networks.
What is the correct answer to this question?
The correct answer is: ARP spoofing — DAI validates ARP packets, helping block ARP spoofing and poisoning on access networks.
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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