The answer is DNS poisoning. This attack is correctly identified because DNS cache poisoning, also known as DNS cache poisoning, occurs when an attacker inserts forged DNS resource records into a local DNS cache, causing subsequent queries for a legitimate domain to resolve to an attacker-controlled IP address. In the described scenario, users type the correct website name, but because the local DNS cache has been altered, their browsers are redirected to a fake server, which directly matches this technical definition. On the Security+ SY0-701 exam, this question tests your understanding of how DNS integrity failures lead to redirection attacks, often appearing in scenarios where the user enters the correct URL but lands on a malicious site. A common trap is confusing this with phishing or man-in-the-middle attacks, but the key clue is the altered local cache. Remember the mnemonic: "Poisoned cache, wrong address—DNS is the mess."
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 can reach the correct website name, but their browsers are redirected to a fake server after the local DNS cache is altered. 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.
DNS poisoning changes name-resolution information so users are sent to the wrong IP address. If the cache points a real name to a fake server, DNS poisoning is the most likely cause.
B
Denial of service
Why wrong: Denial of service focuses on making a service unavailable, not silently redirecting users to a fake site.
C
Replay attack
Why wrong: A replay attack reuses captured valid traffic, such as an authentication message, instead of altering DNS records.
D
Port scanning
Why wrong: Port scanning is reconnaissance used to discover open services, not a redirection attack on name resolution.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
DNS poisoning
DNS poisoning (also known as DNS cache poisoning) occurs when an attacker inserts forged DNS resource records into the local DNS cache, causing subsequent queries for a legitimate domain to resolve to an attacker-controlled IP address. In this scenario, users type the correct website name, but because the local DNS cache has been altered, their browsers are redirected to a fake server. This directly matches the description of DNS poisoning.
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.
✓
DNS poisoning
Why this is correct
DNS poisoning changes name-resolution information so users are sent to the wrong IP address. If the cache points a real name to a fake server, DNS poisoning is the most likely cause.
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.
✗
Denial of service
Why it's wrong here
Denial of service focuses on making a service unavailable, not silently redirecting users to a fake site.
✗
Replay attack
Why it's wrong here
A replay attack reuses captured valid traffic, such as an authentication message, instead of altering DNS records.
✗
Port scanning
Why it's wrong here
Port scanning is reconnaissance used to discover open services, not a redirection attack on name resolution.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse DNS poisoning with a man-in-the-middle attack or think that altering the local hosts file is the same mechanism, but the question specifically states the local DNS cache is altered, which is the hallmark of DNS cache poisoning.
Detailed technical explanation
How to think about this question
DNS cache poisoning exploits the lack of authentication in traditional DNS queries (before DNSSEC). An attacker can send a forged DNS response with a spoofed source IP (the legitimate DNS server) and a matching transaction ID, causing the resolver to cache the malicious A record. In a real-world scenario, this could be used to redirect users to a phishing site that mimics the legitimate website, capturing credentials or other sensitive data.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SY0-701 question in full detail.
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 — DNS poisoning (also known as DNS cache poisoning) occurs when an attacker inserts forged DNS resource records into the local DNS cache, causing subsequent queries for a legitimate domain to resolve to an attacker-controlled IP address. In this scenario, users type the correct website name, but because the local DNS cache has been altered, their browsers are redirected to a fake server. This directly matches the description of DNS poisoning.
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.
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