- A
enable DHCP snooping so trusted IP-to-MAC bindings can be validated
DHCP snooping builds a trusted binding table that helps security controls distinguish valid host mappings from forged ones. On many managed switches, that table is used to support protections against spoofed layer 2 traffic. It is a standard companion control for preventing local network poisoning attacks.
- B
enable dynamic ARP inspection to block forged ARP replies
Dynamic ARP inspection checks ARP traffic against trusted bindings and drops replies that do not match expected IP-to-MAC associations. That makes it one of the most effective mitigations for ARP spoofing or poisoning on managed switches. It directly addresses the bad ARP replies described in the capture.
- C
change the default gateway IP address on the subnet
Why wrong: Changing the gateway address does not stop an attacker from forging ARP responses on the local segment. The poisoning issue is about false layer 2 mappings, not the specific gateway IP value. This would create administrative work without addressing the root cause.
- D
disable spanning tree protocol to reduce switching delays
Why wrong: Spanning tree is unrelated to ARP poisoning and should not be disabled as a response to spoofed ARP traffic. Turning it off can actually create loops and instability on the network. This option addresses the wrong problem and could make the environment less reliable.
- E
replace private addressing with NAT on every endpoint
Why wrong: Network address translation does not prevent layer 2 spoofing on a local subnet. The attack happens before traffic leaves the segment, so NAT is not the right mitigation. This would not stop forged ARP replies from redirecting traffic.
Quick Answer
The answer is to enable Dynamic ARP Inspection (DAI) and DHCP Snooping on the managed switches. This is correct because ARP spoofing attacks rely on sending forged, unsolicited ARP replies to redirect traffic, and DAI validates every ARP packet against a trusted database of IP-to-MAC bindings created by DHCP Snooping. Without DHCP Snooping, DAI has no reliable source of truth to compare against, making it ineffective. On the Security+ SY0-701 exam, this scenario tests your understanding of layer 2 security controls and how they chain together—attackers often target the default gateway to perform man-in-the-middle attacks. A common trap is choosing port security or 802.1X, which control device access but do not inspect ARP messages. Remember the memory tip: “Snoop first, then Inspect”—DHCP Snooping builds the map, and DAI enforces the traffic rules.
SY0-701 Threats, Vulnerabilities, and Mitigations Practice Question
This SY0-701 practice question tests your understanding of threats, vulnerabilities, and mitigations. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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.
Users on one VLAN report that their traffic to the default gateway is intermittently slow and sometimes reaches the wrong device. A packet capture shows unsolicited ARP replies claiming to be the gateway. Which two actions are the best mitigations on managed switches? Select two.
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
enable DHCP snooping so trusted IP-to-MAC bindings can be validated
Option A is correct because DHCP snooping creates a trusted database of IP-to-MAC bindings by monitoring DHCP messages. This database is then used by Dynamic ARP Inspection (DAI) to validate ARP packets, ensuring that only legitimate gateway addresses are accepted. Without DHCP snooping, DAI has no reliable source of truth to compare against, making it ineffective against ARP spoofing attacks.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
enable DHCP snooping so trusted IP-to-MAC bindings can be validated
Why this is correct
DHCP snooping builds a trusted binding table that helps security controls distinguish valid host mappings from forged ones. On many managed switches, that table is used to support protections against spoofed layer 2 traffic. It is a standard companion control for preventing local network poisoning attacks.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
enable dynamic ARP inspection to block forged ARP replies
Why this is correct
Dynamic ARP inspection checks ARP traffic against trusted bindings and drops replies that do not match expected IP-to-MAC associations. That makes it one of the most effective mitigations for ARP spoofing or poisoning on managed switches. It directly addresses the bad ARP replies described in the capture.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
change the default gateway IP address on the subnet
- ✗
disable spanning tree protocol to reduce switching delays
Why it's wrong here
Spanning tree is unrelated to ARP poisoning and should not be disabled as a response to spoofed ARP traffic. Turning it off can actually create loops and instability on the network. This option addresses the wrong problem and could make the environment less reliable.
- ✗
replace private addressing with NAT on every endpoint
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the dependency between DHCP snooping and Dynamic ARP Inspection, so candidates may incorrectly select DAI alone without realizing that DHCP snooping must be enabled first to populate the binding table.
Detailed technical explanation
How to think about this question
Dynamic ARP Inspection (DAI) intercepts all ARP packets on untrusted ports and verifies them against the DHCP snooping binding table. If an ARP reply claims to be the gateway but the source MAC or IP does not match the binding, DAI drops the packet. In a real-world scenario, an attacker on the same VLAN could send gratuitous ARP replies with the gateway's IP and their own MAC, causing traffic to be redirected to them; DAI prevents this by only allowing ARP replies that match the trusted database.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this SY0-701 question test?
Threats, Vulnerabilities, and Mitigations — This question tests Threats, Vulnerabilities, and Mitigations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: enable DHCP snooping so trusted IP-to-MAC bindings can be validated — Option A is correct because DHCP snooping creates a trusted database of IP-to-MAC bindings by monitoring DHCP messages. This database is then used by Dynamic ARP Inspection (DAI) to validate ARP packets, ensuring that only legitimate gateway addresses are accepted. Without DHCP snooping, DAI has no reliable source of truth to compare against, making it ineffective against ARP spoofing attacks.
What should I do if I get this SY0-701 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This SY0-701 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SY0-701 exam.
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