Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Users on a wired subnet report intermittent outages when reaching an internal application. A packet capture shows the default gateway IP address repeatedly mapped to a different workstation MAC address, and traffic is being forwarded through that workstation. What attack is most likely occurring?
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
DNS poisoning, because the hostname is resolving to the wrong server.
DNS poisoning affects name resolution records, but the evidence here is specifically about ARP mappings for the gateway.
B
Best answer
ARP spoofing, because false Layer 2 address mappings are redirecting traffic.
ARP spoofing, also called ARP poisoning, happens when a host sends forged ARP messages that associate a target IP address with the attacker’s MAC address. In this case, the gateway IP is repeatedly being mapped to a workstation MAC, and traffic is being relayed through that workstation. That is a classic man-in-the-middle setup on a local network segment.
C
Distractor review
Replay attack, because packets are being resent to the gateway.
Replay attacks reuse captured authentication or transaction data, but the key issue here is address mapping manipulation, not repeated packet reuse.
D
Distractor review
Rogue DHCP service, because clients are losing access to the default gateway.
A rogue DHCP server would hand out bad network settings to clients, but the capture points to forged ARP replies on an active subnet.
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: ARP spoofing, because false Layer 2 address mappings are redirecting traffic. — The most likely attack is ARP spoofing. The attacker is falsifying MAC-to-IP mappings so the gateway IP resolves to the attacker-controlled workstation, allowing traffic interception or modification. The symptoms strongly indicate a local man-in-the-middle attack at Layer 2. Investigators should look for gratuitous ARP replies, duplicate IP-to-MAC mappings, and abnormal traffic forwarding behavior on the compromised host. Why others are wrong: DNS poisoning would alter DNS results, not the ARP cache for the gateway. A replay attack involves resending captured data, which is not what the packet capture shows. A rogue DHCP server can cause misconfiguration, but the repeated gateway MAC mapping is more directly explained by ARP spoofing and the resulting man-in-the-middle positioning.
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.
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