The answer is the authentication server, typically a RADIUS server, which validates user credentials against an identity store. In the 802.1X authentication framework, the supplicant (the client device) submits credentials, and the authenticator (a switch or wireless access point) relays those credentials via EAP frames, but it is the authentication server that performs the actual verification against a directory like Active Directory or LDAP. On the ISC2 Certified in Cybersecurity CC exam, this question tests your understanding of the three core 802.1X roles—supplicant, authenticator, and authentication server—and a common trap is confusing the authenticator’s relay function with the authentication decision. Remember that the authenticator only controls port access; it never checks passwords. A useful memory tip: think of the RADIUS server as the “bouncer” who checks the ID, while the switch is just the door that opens after the bouncer says yes.
ISC2 CC Network Security Practice Question
This CC practice question tests your understanding of network security. 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 company's network uses 802.1X authentication for wired and wireless access. Which component authenticates the user credentials against an identity store?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Authentication server (RADIUS)
In 802.1X, the authentication server (typically a RADIUS server) is the component that validates user credentials against an identity store such as LDAP, Active Directory, or a local database. The supplicant (client) provides credentials, the authenticator (switch or access point) relays EAP frames, but only the RADIUS server performs the actual authentication decision.
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.
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Supplicant
Why it's wrong here
The supplicant is the client software requesting access, not the authenticating component.
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Authenticator
Why it's wrong here
The authenticator (e.g., switch or AP) relays credentials but does not verify them.
✓
Authentication server (RADIUS)
Why this is correct
The authentication server performs the actual credential verification against the identity store.
Related concept
Read the scenario before looking for a memorised answer.
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Access point
Why it's wrong here
The access point acts as an authenticator in wireless networks; it does not authenticate against the identity store directly.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the misconception that the authenticator (switch or AP) performs authentication, but in 802.1X the authenticator only controls port access based on the RADIUS server's decision, not the credential validation itself.
Detailed technical explanation
How to think about this question
Under the hood, 802.1X uses EAP (Extensible Authentication Protocol) over LAN (EAPoL) for wired or EAP over RADIUS for the server communication. The RADIUS server processes EAP methods (e.g., EAP-TLS, PEAP-MSCHAPv2) and returns an Access-Accept or Access-Reject message. In a real-world scenario, if the RADIUS server is unreachable, the authenticator may fall back to a local VLAN or guest access, but it never performs the authentication itself.
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 analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Network Security — This question tests Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Authentication server (RADIUS) — In 802.1X, the authentication server (typically a RADIUS server) is the component that validates user credentials against an identity store such as LDAP, Active Directory, or a local database. The supplicant (client) provides credentials, the authenticator (switch or access point) relays EAP frames, but only the RADIUS server performs the actual authentication decision.
What should I do if I get this CC 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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