- A
ARP spoofing or poisoning is occurring on the local network.
The evidence fits ARP poisoning because an unauthorized MAC address is associating itself with trusted IP addresses such as the gateway and DNS server. Gratuitous ARP replies reinforce the cache manipulation and allow the attacker to redirect traffic at the layer 2 level. This is the classic setup for a local network spoofing attack.
- B
A man-in-the-middle interception is likely happening between clients and internal services.
If the attacker controls address resolution for the gateway and DNS server, client traffic can be forced through the malicious host. That positions the attacker to observe, relay, or modify traffic without immediate detection. The captured symptoms strongly indicate an active man-in-the-middle path rather than only a passive spoofing attempt.
- C
The network is experiencing a SYN flood against the gateway.
Why wrong: A SYN flood would show large volumes of half-open TCP sessions and connection-state exhaustion, not ARP cache manipulation. The evidence here is focused on layer 2 address association and forged replies, which does not match a denial-of-service pattern targeting TCP handshake resources.
- D
An external host is performing broad port scanning on public services.
Why wrong: Port scanning would appear as repeated connection attempts across many ports or hosts, usually from a source probing for open services. The symptoms here involve local broadcast behavior and cache poisoning, not enumeration of exposed TCP or UDP ports across the perimeter.
- E
A password-spraying campaign is targeting remote logins.
Why wrong: Password spraying would produce authentication failures and occasional successful logins, typically in logs from identity providers or VPN systems. It would not explain forged ARP replies or a changed MAC association for the gateway and DNS server. This is a different attack family entirely.
Quick Answer
The answer is a man-in-the-middle interception achieved through ARP spoofing. This is correct because the packet capture shows the default gateway IP mapped to a rogue MAC address, and the same MAC also answers for the DNS server IP, which are classic signs of an attacker forging ARP replies to redirect traffic through their machine. Gratuitous ARP replies sent every 30 seconds confirm the attacker is actively maintaining the poisoned cache entries, allowing them to intercept and potentially modify traffic between clients and internal services. On the Security+ SY0-701 exam, this scenario tests your ability to recognize ARP spoofing as a Layer 2 attack that breaks the normal IP-to-MAC binding; a common trap is confusing it with DHCP snooping or DNS poisoning. Remember the memory tip: "One MAC, many IPs—that's a spoofing trip."
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.
A packet capture from a branch office shows the default gateway IP mapped to a MAC address that does not belong to the router. The same suspicious MAC also answers for the DNS server IP, and gratuitous ARP replies appear every 30 seconds. Which two attacks best match this evidence? 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
ARP spoofing or poisoning is occurring on the local network.
Option A is correct because the evidence shows the default gateway IP is mapped to a MAC address that does not belong to the router, and the same suspicious MAC also answers for the DNS server IP. This is a classic indicator of ARP spoofing or poisoning, where an attacker sends forged ARP replies to associate their MAC address with the IP addresses of critical network devices, such as the gateway and DNS server. Gratuitous ARP replies every 30 seconds further confirm an active ARP poisoning attack, as the attacker repeatedly broadcasts these unsolicited replies to maintain the poisoned ARP cache entries on victim hosts.
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.
- ✓
ARP spoofing or poisoning is occurring on the local network.
Why this is correct
The evidence fits ARP poisoning because an unauthorized MAC address is associating itself with trusted IP addresses such as the gateway and DNS server. Gratuitous ARP replies reinforce the cache manipulation and allow the attacker to redirect traffic at the layer 2 level. This is the classic setup for a local network spoofing attack.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
A man-in-the-middle interception is likely happening between clients and internal services.
Why this is correct
If the attacker controls address resolution for the gateway and DNS server, client traffic can be forced through the malicious host. That positions the attacker to observe, relay, or modify traffic without immediate detection. The captured symptoms strongly indicate an active man-in-the-middle path rather than only a passive spoofing attempt.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The network is experiencing a SYN flood against the gateway.
Why it's wrong here
A SYN flood would show large volumes of half-open TCP sessions and connection-state exhaustion, not ARP cache manipulation. The evidence here is focused on layer 2 address association and forged replies, which does not match a denial-of-service pattern targeting TCP handshake resources.
- ✗
An external host is performing broad port scanning on public services.
- ✗
A password-spraying campaign is targeting remote logins.
Why it's wrong here
Password spraying would produce authentication failures and occasional successful logins, typically in logs from identity providers or VPN systems. It would not explain forged ARP replies or a changed MAC association for the gateway and DNS server. This is a different attack family entirely.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse ARP spoofing with a SYN flood or other denial-of-service attacks, failing to recognize that the specific evidence of a mismatched MAC address and gratuitous ARP replies directly points to ARP cache poisoning, not a network-level flood.
Trap categories for this question
Command / output trap
A SYN flood would show large volumes of half-open TCP sessions and connection-state exhaustion, not ARP cache manipulation. The evidence here is focused on layer 2 address association and forged replies, which does not match a denial-of-service pattern targeting TCP handshake resources.
Detailed technical explanation
How to think about this question
ARP spoofing exploits the stateless nature of ARP, where hosts accept unsolicited ARP replies without verification, as defined in RFC 826. An attacker can use tools like Ettercap or arpspoof to send gratuitous ARP replies, poisoning the ARP cache of all hosts on the local broadcast domain. This allows the attacker to intercept traffic between clients and the gateway or DNS server, enabling man-in-the-middle attacks, data sniffing, or session hijacking.
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 team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
What to study next
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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: ARP spoofing or poisoning is occurring on the local network. — Option A is correct because the evidence shows the default gateway IP is mapped to a MAC address that does not belong to the router, and the same suspicious MAC also answers for the DNS server IP. This is a classic indicator of ARP spoofing or poisoning, where an attacker sends forged ARP replies to associate their MAC address with the IP addresses of critical network devices, such as the gateway and DNS server. Gratuitous ARP replies every 30 seconds further confirm an active ARP poisoning attack, as the attacker repeatedly broadcasts these unsolicited replies to maintain the poisoned ARP cache entries on victim hosts.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
2 more ways this is tested on SY0-701
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Users on a branch VLAN intermittently reach a fake login page even though DNS records have not changed. A packet capture shows the default gateway MAC address changing every 60 seconds, and the switch logs list repeated unsolicited ARP replies from one workstation. Which attack is most likely?
hard- A.DNS poisoning, because name resolution is directing users to the wrong server.
- ✓ B.ARP poisoning, because forged ARP replies are associating the gateway IP with the attacker's MAC address.
- C.Replay attack, because previously captured traffic is being resent to the network.
- D.Denial of service, because the branch users cannot reliably reach websites.
Why B: The repeated unsolicited ARP replies from one workstation, combined with the default gateway MAC address changing every 60 seconds, directly indicate an ARP poisoning attack. The attacker is sending forged ARP replies to associate the gateway IP with its own MAC address, causing traffic destined for the gateway to be intercepted. This allows the attacker to redirect users to a fake login page without altering DNS records.
Variation 2. Users on the same VLAN report that their browser occasionally reaches a fake internal portal, and packet captures show one host sending forged ARP replies that claim to be the default gateway. Traffic from nearby systems begins flowing through that host. Which attack is occurring?
medium- A.DNS poisoning
- ✓ B.ARP spoofing
- C.MAC flooding
- D.SYN flood
Why B: B is correct because the scenario describes ARP spoofing (also known as ARP poisoning). The attacker sends forged ARP replies to associate their MAC address with the default gateway's IP address, causing traffic from other hosts on the same VLAN to be redirected through the attacker's machine. This allows the attacker to intercept, modify, or redirect traffic to a fake internal portal, which is a classic man-in-the-middle (MITM) attack leveraging the stateless nature of ARP.
Last reviewed: Jun 11, 2026
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