The correct answer is to add a RADIUS provider with IP 10.10.10.10 and secret 'SecureSecret123', create a login domain with realm 'radius', set fallback to 'local', and assign the domain to users. This configuration is necessary because Cisco APIC relies on a login domain to define the authentication method; by setting the realm to 'radius', the APIC directs all management authentication requests to the specified RADIUS server, which can then issue an OTP challenge for MFA. The fallback to local ensures that if the RADIUS server becomes unreachable, administrators are not locked out, maintaining operational continuity. On the Cisco DCCOR 350-601 exam, this scenario tests your understanding of AAA integration within ACI, specifically the distinction between creating a RADIUS provider group versus a login domain—a common trap is forgetting to assign the domain to users or omitting the fallback parameter. Remember the sequence: provider first, then domain with realm and fallback, then user assignment; think "Provider, Domain, Assign" as a quick memory aid for the ACI MFA RADIUS authentication workflow.
350-601 Security Practice Question
This 350-601 practice question tests your understanding of 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 large financial institution has a Cisco ACI fabric with multiple tenants. The security team requires that all management access to the APIC controllers be authenticated via multi-factor authentication (MFA) using a RADIUS server. The RADIUS server is configured to send a One-Time Password (OTP) challenge during authentication. The current configuration uses local authentication. The engineer needs to implement RADIUS authentication with MFA for APIC GUI and CLI access. The RADIUS server is reachable at 10.10.10.10, shared secret 'SecureSecret123'. The APIC is running software version 4.2(3). The engineer must ensure that local authentication is used as fallback if the RADIUS server is unreachable. Which of the following actions should the engineer take?
Configure TACACS+ as the authentication protocol and set the server IP and secret.
Why wrong: The requirement is RADIUS, not TACACS+.
B
Enable local authentication only and require strong passwords.
Why wrong: MFA is required; local alone does not provide MFA.
C
Add a RADIUS provider with IP 10.10.10.10 and secret 'SecureSecret123', create a login domain with realm 'radius', set fallback to 'local', and assign the domain to users.
Correct: RADIUS with PAP is used for MFA and fallback to local.
D
Configure LDAP authentication with the RADIUS server acting as an LDAP proxy.
Why wrong: LDAP is not designed for OTP challenges.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a RADIUS provider with IP 10.10.10.10 and secret 'SecureSecret123', create a login domain with realm 'radius', set fallback to 'local', and assign the domain to users.
Option C is correct because it follows the required steps to configure RADIUS authentication with MFA on Cisco APIC: adding a RADIUS provider with the correct IP and shared secret, creating a login domain with realm 'radius', setting fallback to 'local', and assigning the domain to users. This ensures that the APIC sends authentication requests to the RADIUS server, which can issue an OTP challenge for MFA, and falls back to local authentication if the RADIUS server is unreachable.
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.
✗
Configure TACACS+ as the authentication protocol and set the server IP and secret.
Enable local authentication only and require strong passwords.
Why it's wrong here
MFA is required; local alone does not provide MFA.
✓
Add a RADIUS provider with IP 10.10.10.10 and secret 'SecureSecret123', create a login domain with realm 'radius', set fallback to 'local', and assign the domain to users.
Why this is correct
Correct: RADIUS with PAP is used for MFA and fallback to local.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure LDAP authentication with the RADIUS server acting as an LDAP proxy.
Why it's wrong here
LDAP is not designed for OTP challenges.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the requirement to create a login domain and assign it to users, as many candidates mistakenly think simply adding a RADIUS provider is sufficient without configuring the domain and fallback.
Detailed technical explanation
How to think about this question
In Cisco ACI, authentication is handled through login domains that map to authentication providers (e.g., RADIUS). When a RADIUS provider is configured with a shared secret and the APIC sends an Access-Request, the RADIUS server can respond with an Access-Challenge containing a state attribute and a reply message prompting for an OTP. The fallback to local authentication is configured at the login domain level, ensuring that if the RADIUS server is unreachable (e.g., due to network failure), the APIC uses the local database for authentication, preventing lockout.
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 junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
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 — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a RADIUS provider with IP 10.10.10.10 and secret 'SecureSecret123', create a login domain with realm 'radius', set fallback to 'local', and assign the domain to users. — Option C is correct because it follows the required steps to configure RADIUS authentication with MFA on Cisco APIC: adding a RADIUS provider with the correct IP and shared secret, creating a login domain with realm 'radius', setting fallback to 'local', and assigning the domain to users. This ensures that the APIC sends authentication requests to the RADIUS server, which can issue an OTP challenge for MFA, and falls back to local authentication if the RADIUS server is unreachable.
What should I do if I get this 350-601 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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