Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Which switch security feature uses DHCP snooping bindings to validate ARP packets and help stop ARP spoofing?
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
PortFast
PortFast is used for fast edge-port transition, not ARP validation.
B
Best answer
Dynamic ARP Inspection
Correct. DAI is designed to mitigate ARP spoofing.
C
Distractor review
UDLD
UDLD addresses unidirectional link problems, not ARP spoofing.
D
Distractor review
HSRP preemption
HSRP preemption concerns first-hop redundancy.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is selecting PortFast, UDLD, or HSRP preemption as the answer because these features are well-known switch security or stability mechanisms. However, PortFast only speeds up STP port transitions and does not inspect ARP packets. UDLD focuses on detecting unidirectional links and does not validate ARP traffic. HSRP preemption deals with gateway redundancy and has no role in ARP security. The key to avoiding this trap is recognizing that only Dynamic ARP Inspection uses DHCP snooping bindings to validate ARP packets and stop ARP spoofing.
Technical deep dive
How to think about this question
Dynamic ARP Inspection (DAI) is a security feature implemented on Cisco switches to prevent ARP spoofing attacks. ARP spoofing occurs when a malicious device sends forged ARP messages onto a LAN, associating its MAC address with the IP address of another host, which can lead to man-in-the-middle attacks or denial of service. DAI works by intercepting all ARP packets on untrusted ports and validating them against a trusted database of IP-to-MAC bindings, typically learned through DHCP snooping. This ensures only legitimate ARP requests and replies are forwarded, blocking any forged or malicious ARP packets. The validation process in DAI relies heavily on DHCP snooping bindings, which record the IP address, MAC address, lease time, binding type, VLAN, and interface of DHCP clients. When an ARP packet is received, DAI compares the sender's IP and MAC addresses against the DHCP snooping table. If the packet does not match a valid binding or comes from an untrusted port, DAI drops the packet. This mechanism effectively stops ARP spoofing by ensuring that only ARP packets with valid IP-MAC mappings are allowed, protecting the integrity of the Layer 2 network. A common exam trap is confusing DAI with other security features like PortFast, UDLD, or HSRP preemption. PortFast accelerates STP convergence but does not validate ARP packets. UDLD detects unidirectional links but does not inspect ARP traffic. HSRP preemption manages first-hop redundancy and does not provide ARP security. Understanding that DAI specifically uses DHCP snooping bindings to validate ARP packets is critical for correctly answering questions about switch security features that prevent ARP spoofing.
KKey Concepts to Remember
- Dynamic ARP Inspection uses DHCP snooping bindings to validate ARP packets and prevent ARP spoofing attacks on Cisco switches.
- DAI intercepts ARP packets on untrusted ports and compares sender IP and MAC addresses against trusted DHCP snooping tables before forwarding.
- DHCP snooping records IP-to-MAC bindings dynamically, providing the trusted database that DAI uses to verify ARP packet legitimacy.
- DAI blocks forged ARP packets that do not match DHCP snooping bindings, protecting the network from man-in-the-middle and denial-of-service attacks.
- PortFast accelerates STP port transitions but does not perform ARP packet validation or prevent ARP spoofing.
- UDLD detects unidirectional link failures but does not inspect or validate ARP traffic for security purposes.
- HSRP preemption manages first-hop redundancy protocols and does not provide protection against ARP spoofing or ARP packet validation.
- DAI must be enabled on switches with DHCP snooping configured to effectively secure ARP traffic and prevent spoofing attacks.
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
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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 uses DHCP snooping bindings to validate ARP packets and prevent ARP spoofing attacks on Cisco switches.
What is the correct answer to this question?
The correct answer is: Dynamic ARP Inspection — Dynamic ARP Inspection compares ARP information to trusted bindings, often learned through DHCP snooping, to block forged ARP packets.
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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