The answer is the RADIUS server’s certificate not being trusted by the new laptop. This is correct because EAP-TLS requires mutual authentication: the client must validate the RADIUS server’s certificate against a trusted root CA, just as the server validates the client’s certificate. If the new laptop lacks the necessary root CA certificate—or has an expired one—the EAP-TLS handshake fails, while older laptops with the root CA installed connect successfully. On the CISSP exam, this scenario tests your understanding of Public Key Infrastructure (PKI) trust chains within 802.1X authentication, often appearing as a trap where candidates focus only on the client certificate. Remember the key insight: in EAP-TLS, trust flows both ways. A useful memory tip is “Server first, client next”—the client must trust the server’s certificate before the server will trust the client’s.
CISSP Communication and Network Security Practice Question
This CISSP practice question tests your understanding of communication and network security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 company uses WPA2-Enterprise with EAP-TLS for wireless access. An employee reports that a new laptop cannot connect to the wireless network, while older laptops work fine. The employee has installed the correct client certificate. What is the most likely cause?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The RADIUS server's certificate is not trusted by the new laptop.
In WPA2-Enterprise with EAP-TLS, mutual authentication requires the client to validate the RADIUS server's certificate. If the new laptop does not trust the RADIUS server's certificate (e.g., its CA root certificate is missing or expired), the EAP-TLS handshake will fail, preventing connection. Older laptops likely have the necessary root CA installed, while the new laptop does not.
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.
✗
The wireless network uses WPA2-PSK instead of WPA2-Enterprise.
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse EAP-TLS with EAP-PEAP or EAP-TTLS, which use MSCHAPv2 for inner authentication, and incorrectly assume the issue is MSCHAPv2 support, when in fact EAP-TLS relies solely on certificate trust.
Detailed technical explanation
How to think about this question
EAP-TLS uses a TLS handshake where the client verifies the RADIUS server's certificate against a trusted root CA store (often via a certificate chain). If the server's certificate is self-signed or issued by an internal CA whose root certificate is not installed on the client, the client will reject the connection with a certificate validation error. In real-world deployments, this often occurs when IT provisions new devices without pre-installing the internal CA certificate, while older devices already have it from a previous configuration.
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 developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Communication and Network Security — This question tests Communication and Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The RADIUS server's certificate is not trusted by the new laptop. — In WPA2-Enterprise with EAP-TLS, mutual authentication requires the client to validate the RADIUS server's certificate. If the new laptop does not trust the RADIUS server's certificate (e.g., its CA root certificate is missing or expired), the EAP-TLS handshake will fail, preventing connection. Older laptops likely have the necessary root CA installed, while the new laptop does not.
What should I do if I get this CISSP 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
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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. A network engineer is configuring 802.1X authentication for wired network access. The authentication server supports EAP-TLS. What must be deployed to clients to support this authentication method?
medium
✓ A.Client certificate
B.Server certificate
C.RADIUS server
D.Shared secret
Why A: EAP-TLS requires mutual authentication using digital certificates on both the client and the server. The client must present a certificate to prove its identity to the authentication server, which is validated against a trusted root CA. Without a client certificate, EAP-TLS cannot establish the TLS tunnel, as it relies on certificate-based client authentication per RFC 5216.
Last reviewed: Jun 11, 2026
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This CISSP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISSP exam.
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