Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Exhibit
Packet Capture Summary Host 10.20.30.44 sends repeated ARP replies: "10.20.30.1 is at 00:11:22:33:44:55" "10.20.30.1 is at 00:11:22:33:44:55" Switch logs: DHCP snooping: disabled ARP inspection: disabled Users report intermittent gateway connectivity and traffic sent to the wrong MAC address.
Based on the exhibit, which control should be enabled to mitigate this issue?
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
DNSSEC, because it validates DNS records and would stop local address-to-MAC spoofing.
DNSSEC protects DNS data integrity, but this incident is about forged ARP replies on a local subnet. ARP operates below DNS and is used to resolve IP addresses to MAC addresses. DNSSEC would not stop the bad ARP mappings shown in the capture.
B
Distractor review
Port forwarding, because it can direct traffic to the correct internal host more reliably.
Port forwarding is a routing or NAT convenience mechanism, not a protection against forged Layer 2 address resolution. The problem here is that clients are learning a fake MAC address for the gateway. Forwarding does not validate ARP or stop spoofed replies.
C
Distractor review
Load balancing, because it would distribute traffic and reduce the impact of connectivity issues.
Load balancing improves availability for services, but it does not detect or prevent ARP poisoning on a local broadcast domain. The exhibit shows hosts being tricked into using the wrong MAC address, which must be addressed with a Layer 2 security control.
D
Best answer
Dynamic ARP inspection with DHCP snooping, because it validates ARP replies against trusted bindings.
Dynamic ARP inspection is designed to block forged ARP messages by checking them against trusted information, usually built from DHCP snooping bindings. Since the switch logs show both DHCP snooping and ARP inspection disabled, enabling these controls is the most appropriate mitigation for the poisoning behavior described.
Common exam trap
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Technical deep dive
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
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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 laptop is suspected of being used in a malware incident. It is still powered on and connected to Wi-Fi. What should the responder do before shutting it down?
Question 2
An employee reports a ransomware note on a file server. The server is still powered on, shares are still being accessed, and management wants service restored as quickly as possible. What should the incident response team do first?
Question 3
An employee reports a ransomware note on a finance laptop. The laptop is still powered on, connected to Wi-Fi, and the user says they were just working in a spreadsheet. Management wants the fastest safe response that also preserves evidence. What should the responder do first?
Question 4
You are handed a company laptop suspected in an insider theft case. Legal says the evidence may be needed in court. Which action best preserves admissibility?
Question 5
A developer wants to reduce the risk of SQL injection in a new customer search form. Which two changes are the best mitigations? Select two.
Question 6
A branch office uses a flat LAN, and a compromise on one user workstation could spread quickly to finance systems. Management wants finance workstations isolated from general users, but finance staff still need access to a central finance application and network printer. What is the best design change?
FAQ
Questions learners often ask
What does this SY0-701 question test?
CIDR notation defines the prefix length.
What is the correct answer to this question?
The correct answer is: Dynamic ARP inspection with DHCP snooping, because it validates ARP replies against trusted bindings. — Dynamic ARP inspection with DHCP snooping is the best mitigation. The exhibit shows repeated ARP replies claiming the gateway IP belongs to a specific MAC address, which is classic ARP poisoning behavior. DAI uses trusted DHCP snooping bindings to verify whether an ARP message is legitimate before it is allowed on the network. That prevents an attacker from redirecting traffic to the wrong device. Why others are wrong: DNSSEC protects DNS records, not ARP cache poisoning on a local subnet. Port forwarding does not validate Layer 2 address resolution and would not stop the attack. Load balancing addresses service availability, not spoofed ARP replies. The scenario needs a Layer 2 anti-spoofing control, not a routing or resiliency feature.
What should I do if I get this SY0-701 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
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