The answer is the Certification Authority (CA) private key. This is correct because a PKI’s entire chain of trust depends on the secrecy of the CA’s private key; if it is compromised, an attacker can sign fraudulent certificates that any client trusting that CA will accept as valid, enabling man-in-the-middle attacks. On the Cisco SCOR / CCNP Security Core 350-701 exam, this scenario tests your understanding of PKI trust models and the devastating impact of a root key breach—a common trap is confusing a compromised CA certificate (which is public) with the private key itself. Remember, the private key is the crown jewel: without it, the attacker cannot forge signatures. A useful memory tip is “Private key = signing power; public key = verification only.”
350-701 Security Concepts Practice Question
This 350-701 practice question tests your understanding of security concepts. 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.
An organization discovers that a man-in-the-middle attack was successfully performed using a forged certificate issued by a trusted CA. The legitimate CA’s private key was compromised. Which PKI component was breached?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Certification Authority (CA) private key
The correct answer is A because the man-in-the-middle attack succeeded due to a forged certificate issued by a trusted CA, which directly implies that the CA's private key was compromised. The CA's private key is the root of trust in a PKI; if it is stolen, an attacker can sign fraudulent certificates that will be trusted by all clients that trust the CA. Without the private key, the attacker could not have created a valid forged certificate.
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.
✓
Certification Authority (CA) private key
Why this is correct
The CA private key is used to sign certificates; its compromise allows forging.
Related concept
Read the scenario before looking for a memorised answer.
✗
Online Certificate Status Protocol (OCSP) responder
Why it's wrong here
OCSP provides real-time revocation status, not certificate issuance.
✗
Registration Authority (RA)
Why it's wrong here
RA verifies identity but does not hold the signing key.
✗
Certificate Revocation List (CRL)
Why it's wrong here
CRL is a list of revoked certificates, not the signing key.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between components that issue certificates (CA) versus those that verify or manage status (OCSP, RA, CRL), and the trap here is confusing the CA's signing role with the RA's identity-verification role or the OCSP/CRL's status-checking role.
Detailed technical explanation
How to think about this question
In a PKI, the CA's private key is used to digitally sign every certificate it issues (per RFC 5280). If this key is compromised, the attacker can issue certificates for any entity (e.g., a bank's domain) that will be trusted by browsers and devices that have the CA's root certificate installed. Real-world incidents like the DigiNotar breach (2011) demonstrate how a CA private key compromise leads to widespread man-in-the-middle attacks because the forged certificates are indistinguishable from legitimate ones until the CA is distrusted.
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 practitioner preparing for the 350-701 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Concepts — This question tests Security Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Certification Authority (CA) private key — The correct answer is A because the man-in-the-middle attack succeeded due to a forged certificate issued by a trusted CA, which directly implies that the CA's private key was compromised. The CA's private key is the root of trust in a PKI; if it is stolen, an attacker can sign fraudulent certificates that will be trusted by all clients that trust the CA. Without the private key, the attacker could not have created a valid forged certificate.
What should I do if I get this 350-701 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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