Quick Answer
The correct additional feature is Dynamic ARP Inspection (DAI). DAI prevents ARP spoofing by intercepting and validating all ARP packets on a switch against the trusted IP-to-MAC binding database built by DHCP snooping, dropping any packet that does not match a legitimate entry. On the CCNA 200-301 v2 exam, this question tests your understanding of how Layer 2 security features work together—DHCP snooping alone only validates DHCP messages, not ARP traffic, so DAI is the direct complement. A common trap is confusing DAI with PortFast or EtherChannel, but those serve entirely different purposes. Remember the memory tip: DAI is the “bouncer” for ARP packets, checking IDs against the DHCP snooping guest list to keep spoofers out.
This 200-301 practice question tests your understanding of network services and security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: dynamic ARP Inspection uses the DHCP snooping binding table to validate ARP packets and prevent IP-to-MAC spoofing attacks on untrusted switch ports.. 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.
A switch has DHCP snooping enabled, but users still experience IP-to-MAC spoofing attacks. Which additional feature should be considered to help address that specific problem?
PortFast
Why wrong: PortFast affects STP convergence behavior, not ARP spoofing validation.
Dynamic ARP Inspection
Correct. DAI directly targets ARP spoofing.
EtherChannel
Why wrong: EtherChannel increases logical bandwidth and redundancy, not ARP validation.
NetFlow
Why wrong: NetFlow provides traffic visibility, not active prevention of ARP spoofing.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Dynamic ARP Inspection
Dynamic ARP Inspection (DAI) validates ARP packets against trusted binding information learned through DHCP snooping, directly preventing IP-to-MAC spoofing. PortFast is used to speed up STP convergence and does not provide ARP security. EtherChannel aggregates multiple links for bandwidth and redundancy but does not inspect ARP traffic. NetFlow is a traffic accounting and monitoring tool, not a security control for ARP spoofing. Therefore, DAI is the correct additional feature to address IP-to-MAC spoofing.
Key principle: Dynamic ARP Inspection uses the DHCP snooping binding table to validate ARP packets and prevent IP-to-MAC spoofing attacks on untrusted switch ports.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
PortFast
When this WOULD be correct
In a scenario where the question asks about optimizing switch port configurations for faster connectivity in a network with no concerns about security, PortFast would be the correct answer. For example, if the question specifies a need to reduce the time it takes for end devices to connect without mentioning security threats, PortFast would be appropriate.
Dynamic ARP Inspection
Related concept
Dynamic ARP Inspection uses the DHCP snooping binding table to validate ARP packets and prevent IP-to-MAC spoofing attacks on untrusted switch ports.
EtherChannel
Why it's wrong here
EtherChannel increases logical bandwidth and redundancy, not ARP validation.
When this WOULD be correct
In a scenario where a question asks about optimizing bandwidth and redundancy for a network segment while ensuring link aggregation, EtherChannel would be the correct answer. For example, if the question focuses on improving throughput between switches without addressing security concerns, EtherChannel would be appropriate.
NetFlow
Why it's wrong here
NetFlow provides traffic visibility, not active prevention of ARP spoofing.
When this WOULD be correct
In a scenario where the exam question asks about monitoring and analyzing traffic patterns to identify unusual behavior or potential security threats, NetFlow would be the correct answer. For example, a question might focus on tools for traffic analysis in a network security context.
Option-by-option analysis
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.
Why this is correct
Correct. DAI directly targets ARP spoofing.
Why this is wrong here
PortFast is a Spanning Tree Protocol feature that immediately transitions a port to forwarding state, bypassing listening and learning states. It does not perform any validation of ARP packets or prevent IP-to-MAC spoofing attacks.
★ When this WOULD be the correct answer
In a scenario where the question asks about optimizing switch port configurations for faster connectivity in a network with no concerns about security, PortFast would be the correct answer. For example, if the question specifies a need to reduce the time it takes for end devices to connect without mentioning security threats, PortFast would be appropriate.
Why candidates choose this
Students might confuse PortFast with a security feature because it is often used on access ports to speed up connectivity, but it has no role in ARP inspection.
Why this is wrong here
EtherChannel is a link aggregation technology that combines multiple physical links into a single logical link to increase bandwidth and provide redundancy. It does not inspect or validate ARP packets, so it cannot prevent IP-to-MAC spoofing.
★ When this WOULD be the correct answer
In a scenario where a question asks about optimizing bandwidth and redundancy for a network segment while ensuring link aggregation, EtherChannel would be the correct answer. For example, if the question focuses on improving throughput between switches without addressing security concerns, EtherChannel would be appropriate.
Why candidates choose this
Students might think EtherChannel provides security through redundancy or load balancing, but it is purely a Layer 2 aggregation feature with no security functions.
Why this is wrong here
NetFlow is a network monitoring protocol that collects IP traffic statistics for analysis and troubleshooting. It provides visibility into traffic patterns but does not actively block or validate ARP packets, so it cannot prevent spoofing attacks.
★ When this WOULD be the correct answer
In a scenario where the exam question asks about monitoring and analyzing traffic patterns to identify unusual behavior or potential security threats, NetFlow would be the correct answer. For example, a question might focus on tools for traffic analysis in a network security context.
Why candidates choose this
Students may confuse NetFlow's traffic analysis capabilities with security features, thinking that monitoring can detect and prevent attacks, but NetFlow is passive and does not enforce security policies.
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
Don't confuse general security features with those specifically designed to prevent ARP spoofing.
Detailed technical explanation
Dynamic ARP Inspection (DAI) is a security feature that validates ARP packets on a network to prevent ARP spoofing attacks. ARP spoofing occurs when a malicious device sends falsified ARP messages, associating its MAC address with the IP address of another host, enabling man-in-the-middle attacks or denial of service. DAI intercepts all ARP requests and replies on untrusted ports and compares them against a trusted database of IP-to-MAC bindings, typically learned via DHCP snooping. If the ARP packet does not match the binding, it is dropped, effectively blocking spoofed ARP messages. The decision process for enabling DAI relies on having DHCP snooping enabled first, as DHCP snooping builds and maintains the IP-to-MAC binding table that DAI uses for validation. Without DHCP snooping, DAI cannot verify ARP packets accurately. DAI is configured on switches to inspect ARP traffic on untrusted ports, while trusted ports (such as uplinks to other switches) are exempted. This layered approach ensures that only legitimate ARP traffic is forwarded, preventing IP-to-MAC spoofing attacks that DHCP snooping alone cannot stop. A common exam trap is assuming that DHCP snooping alone prevents all spoofing attacks. DHCP snooping only validates DHCP messages and builds a binding table but does not inspect ARP packets directly. Candidates might incorrectly select PortFast or EtherChannel, which do not provide ARP validation. In practical networks, enabling DAI alongside DHCP snooping is essential to secure Layer 2 against ARP spoofing. Misconfiguring trusted ports or neglecting to enable DAI can leave the network vulnerable despite DHCP snooping being active.
Key takeaway
Dynamic ARP Inspection uses the DHCP snooping binding table to validate ARP packets and prevent IP-to-MAC spoofing attacks on untrusted switch ports.
Real-world example
A practitioner preparing for the 200-301 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Dynamic ARP Inspection uses the DHCP snooping binding table to validate ARP packets and prevent IP-to-MAC spoofing attacks on untrusted switch ports. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Review dynamic ARP Inspection uses the DHCP snooping binding table to validate ARP packets and prevent IP-to-MAC spoofing attacks on untrusted switch ports., then practise related 200-301 questions on the same topic to reinforce the concept.
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FAQ
Network Services and Security — This question tests Network Services and Security — Dynamic ARP Inspection uses the DHCP snooping binding table to validate ARP packets and prevent IP-to-MAC spoofing attacks on untrusted switch ports..
The correct answer is: Dynamic ARP Inspection — Dynamic ARP Inspection (DAI) validates ARP packets against trusted binding information learned through DHCP snooping, directly preventing IP-to-MAC spoofing. PortFast is used to speed up STP convergence and does not provide ARP security. EtherChannel aggregates multiple links for bandwidth and redundancy but does not inspect ARP traffic. NetFlow is a traffic accounting and monitoring tool, not a security control for ARP spoofing. Therefore, DAI is the correct additional feature to address IP-to-MAC spoofing.
Review dynamic ARP Inspection uses the DHCP snooping binding table to validate ARP packets and prevent IP-to-MAC spoofing attacks on untrusted switch ports., then practise related 200-301 questions on the same topic to reinforce the concept.
Dynamic ARP Inspection uses the DHCP snooping binding table to validate ARP packets and prevent IP-to-MAC spoofing attacks on untrusted switch ports.
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Last reviewed: May 17, 2026
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