- A
ARP spoofing, because the attacker is changing the MAC address used on the local network.
Why wrong: ARP spoofing targets Layer 2 address resolution, usually affecting traffic within the same local segment. The key symptom here is a changed name resolution result in DNS.
- B
DNS poisoning, because the attacker has corrupted name resolution so users are sent to a malicious destination.
DNS poisoning fits the evidence because the resolver cache contains bad entries and users are being directed to a fake site through altered name resolution. That lets the attacker redirect traffic without changing the user’s bookmarks or typing habits.
- C
Port scanning, because the attacker is probing internal services for open ports.
Why wrong: Port scanning is reconnaissance against services, not a method for redirecting a domain name to a counterfeit web page.
- D
Denial-of-service, because the attacker is overwhelming the portal with traffic.
Why wrong: A denial-of-service attack aims to exhaust availability, usually by flooding a target. Here, the attacker is serving a fake destination rather than making the real site unavailable.
Quick Answer
The answer is DNS poisoning, because the attacker has corrupted the name resolution process to redirect users to a malicious IP address. This attack works by injecting forged DNS records into a resolver’s cache, so when users type the finance portal’s hostname, the DNS server returns the attacker’s fake IP instead of the legitimate one. The telltale sign here is the unexpected entries in the DNS resolver cache—ARP spoofing would instead corrupt the MAC-to-IP mapping at Layer 2, not the DNS cache. On the Security+ SY0-701 exam, this scenario tests your ability to distinguish between attacks on name resolution (DNS poisoning) versus attacks on local network addressing (ARP spoofing). A common trap is confusing the two because both can redirect traffic, but DNS poisoning affects all users system-wide, while ARP spoofing is limited to a single subnet. Memory tip: “DNS corrupts the directory, ARP corrupts the address.”
SY0-701 Threats, Vulnerabilities, and Mitigations Practice Question
This SY0-701 practice question tests your understanding of threats, vulnerabilities, and mitigations. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 the internal Wi-Fi report that the finance portal suddenly resolves to a different IP address, and the browser shows a fake login page that closely matches the real site. The DNS resolver cache on the network also contains unexpected entries for that host name. What attack is most likely?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
DNS poisoning, because the attacker has corrupted name resolution so users are sent to a malicious destination.
B is correct because DNS poisoning (also known as DNS cache poisoning) directly corrupts the name resolution process, causing the finance portal's hostname to resolve to a malicious IP address. The presence of unexpected DNS resolver cache entries for that hostname confirms that the attack targeted the DNS infrastructure, not the ARP table or network availability.
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, because the attacker is changing the MAC address used on the local network.
- ✓
DNS poisoning, because the attacker has corrupted name resolution so users are sent to a malicious destination.
Why this is correct
DNS poisoning fits the evidence because the resolver cache contains bad entries and users are being directed to a fake site through altered name resolution. That lets the attacker redirect traffic without changing the user’s bookmarks or typing habits.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Port scanning, because the attacker is probing internal services for open ports.
Why it's wrong here
Port scanning is reconnaissance against services, not a method for redirecting a domain name to a counterfeit web page.
- ✗
Denial-of-service, because the attacker is overwhelming the portal with traffic.
Why it's wrong here
A denial-of-service attack aims to exhaust availability, usually by flooding a target. Here, the attacker is serving a fake destination rather than making the real site unavailable.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse ARP spoofing with DNS poisoning because both can redirect traffic, but ARP spoofing operates at Layer 2 and does not affect DNS resolver cache entries, whereas DNS poisoning directly corrupts the name resolution database.
Detailed technical explanation
How to think about this question
DNS poisoning exploits vulnerabilities in DNS resolver software (e.g., by sending forged DNS responses with a higher transaction ID or using Kaminsky-style attacks) to inject malicious A or AAAA records into the resolver's cache. Once cached, all subsequent queries for the poisoned hostname return the attacker's IP until the TTL expires or the cache is manually cleared. In enterprise environments, this attack can bypass network segmentation because DNS queries traverse internal routers, making it effective even without direct ARP manipulation.
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
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: DNS poisoning, because the attacker has corrupted name resolution so users are sent to a malicious destination. — B is correct because DNS poisoning (also known as DNS cache poisoning) directly corrupts the name resolution process, causing the finance portal's hostname to resolve to a malicious IP address. The presence of unexpected DNS resolver cache entries for that hostname confirms that the attack targeted the DNS infrastructure, not the ARP table or network availability.
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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 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?
medium- A.DNS poisoning, because the hostname is resolving to the wrong server.
- ✓ B.ARP spoofing, because false Layer 2 address mappings are redirecting traffic.
- C.Replay attack, because packets are being resent to the gateway.
- D.Rogue DHCP service, because clients are losing access to the default gateway.
Why B: B is correct because ARP spoofing (also known as ARP poisoning) involves an attacker sending forged ARP messages over a local area network. This results in the attacker's MAC address being associated with the IP address of the default gateway, causing traffic destined for the gateway to be forwarded to the attacker's workstation instead. The packet capture evidence of the default gateway IP repeatedly mapped to a different workstation MAC address is the classic signature of this attack.
Variation 2. Several users on the same subnet report that their traffic to the default gateway is intermittently slow and sometimes reaches the wrong device. A packet capture shows ARP replies that map the gateway IP to a different MAC address. What attack is most likely occurring?
easy- ✓ A.ARP spoofing, which poisons address resolution on the local network
- B.DNS amplification, which overwhelms the target with reflected DNS traffic
- C.Replay attack, which resends captured authentication data
- D.Port scanning, which probes hosts for open services and ports
Why A: ARP spoofing (also known as ARP poisoning) is the correct answer because the attacker sends forged ARP replies that associate the default gateway's IP address with the attacker's MAC address. This causes the victims' switches to update their ARP caches with the false mapping, so traffic destined for the gateway is instead sent to the attacker, leading to intermittent connectivity and misrouted packets. The symptoms—slow traffic and reaching the wrong device—are classic indicators of a man-in-the-middle (MITM) attack via ARP cache poisoning.
Last reviewed: Jun 11, 2026
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