CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and 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.
Network Topology
You are connected to R1. Configure AAA with a RADIUS server at 10.0.0.2/30 (key 'cisco123') so that console and VTY login use RADIUS first, then local authentication. Additionally, troubleshoot why an 802.1X-enabled switch port (GigabitEthernet0/1) on R1 is stuck in the unauthorized state. The RADIUS server is reachable but authentication fails. Verify using 'show aaa servers' and 'show dot1x interface GigabitEthernet0/1 details'.
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
R1# show running-config | section aaa
aaa new-model
aaa authentication login default group radius local
aaa authentication dot1x default group radius
!
radius server RADIUS
address ipv4 10.0.0.2 auth-port 1812 acct-port 1813
key cisco123
!
interface GigabitEthernet0/1
switchport mode access
authentication port-control auto
dot1x pae authenticator
!
R1# show aaa servers
RADIUS: id 1, priority 1, host 10.0.0.2, auth-port 1812, acct-port 1813
State: current UP, duration 120s, previous duration 0s
Dead: total time 0s, count 0
R1# show dot1x interface GigabitEthernet0/1 details
Dot1x Info for GigabitEthernet0/1
-------------------------------
PAE = AUTHENTICATOR
PortControl = AUTO
PortStatus = UNAUTHORIZED
ReAuthentication = Disabled
QuietPeriod = 60
ServerTimeout = 30
SuppTimeout = 30
ReAuthMax = 2
MaxReq = 2
TxPeriod = 30
RateLimitPeriod = 0
AuthMethod = Open
Critical = no
Critical Recovery = no
Guest VLAN = no
Host Mode = Single
Auth-Fail VLAN = no
Vlan Group = no
Capability = n/a
Client Status = not authenticated
Client Mac = 0000.0000.0000
Client IP = 0.0.0.0
Client Username = unknown
Client Auth Protocol = unknown
Client VLAN = 0
Client Session ID = 0
A
Configure 'aaa authentication login default group RADIUS local' and correct the RADIUS server key to match the actual server key.
Using the server name 'RADIUS' as the group correctly forwards AAA requests, and correcting the key resolves the mismatch causing 802.1X failure.
B
Configure 'aaa authentication login default group radius local' and verify the RADIUS server IP address is correct.
Why wrong: This is incorrect because the RADIUS server IP is given as 10.0.0.2/30 and is reachable, so the IP is not the issue. The problem is the shared key mismatch.
C
Configure 'aaa authentication login default group radius local' and enable 802.1X globally with 'dot1x system-auth-control'.
Why wrong: This is incorrect because 802.1X is already enabled on the port (it is stuck in unauthorized state), so global 802.1X is likely already configured. The issue is the RADIUS key mismatch.
D
Configure 'aaa authentication login default local' and remove the RADIUS server configuration.
Why wrong: This is incorrect because the requirement is to use RADIUS first, then local. Using only local authentication bypasses RADIUS entirely, which does not meet the requirement and does not fix the 802.1X issue.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure 'aaa authentication login default group RADIUS local' and correct the RADIUS server key to match the actual server key.
The RADIUS server is reachable but AAA and 802.1X authentication fail because the pre-shared key on R1 does not match the server's actual key. The correct repair is to first apply 'aaa authentication login default group RADIUS local' to correctly reference the RADIUS server by its name, then set the matching key under 'radius server RADIUS'. Once the key matches, the switch port will transition to authorized state.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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 'aaa authentication login default group RADIUS local' and correct the RADIUS server key to match the actual server key.
Why this is correct
Using the server name 'RADIUS' as the group correctly forwards AAA requests, and correcting the key resolves the mismatch causing 802.1X failure.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Authentication checks who the user is.
✗
Configure 'aaa authentication login default group radius local' and verify the RADIUS server IP address is correct.
Why it's wrong here
This is incorrect because the RADIUS server IP is given as 10.0.0.2/30 and is reachable, so the IP is not the issue. The problem is the shared key mismatch.
✗
Configure 'aaa authentication login default group radius local' and enable 802.1X globally with 'dot1x system-auth-control'.
Why it's wrong here
This is incorrect because 802.1X is already enabled on the port (it is stuck in unauthorized state), so global 802.1X is likely already configured. The issue is the RADIUS key mismatch.
✗
Configure 'aaa authentication login default local' and remove the RADIUS server configuration.
Why it's wrong here
This is incorrect because the requirement is to use RADIUS first, then local. Using only local authentication bypasses RADIUS entirely, which does not meet the requirement and does not fix the 802.1X issue.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Configure 'aaa authentication login default group RADIUS local' and correct the RADIUS server key to match the actual server key.Correct answer▾
Why this is correct
Using the server name 'RADIUS' as the group correctly forwards AAA requests, and correcting the key resolves the mismatch causing 802.1X failure.
✗Configure 'aaa authentication login default group radius local' and verify the RADIUS server IP address is correct.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the IP address is already correct and reachable; the failure is due to key mismatch.
Why candidates choose this
Candidates often suspect IP misconfiguration when authentication fails, but here the server is reachable, so IP is not the problem.
✗Configure 'aaa authentication login default group radius local' and enable 802.1X globally with 'dot1x system-auth-control'.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that 802.1X is already enabled; the problem is authentication failure, not missing global configuration.
Why candidates choose this
Candidates may think 802.1X is not fully enabled, but the port is stuck in unauthorized state, indicating it is enabled but failing authentication.
✗Configure 'aaa authentication login default local' and remove the RADIUS server configuration.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the requirement specifies RADIUS first, then local; removing RADIUS violates that and does not address the key mismatch.
Why candidates choose this
Candidates might think local authentication is simpler and will work, but the question explicitly requires RADIUS first.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 200-301 questions on access control and AAA configuration.
Network Services and Security — This question tests Network Services and Security — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Configure 'aaa authentication login default group RADIUS local' and correct the RADIUS server key to match the actual server key. — The RADIUS server is reachable but AAA and 802.1X authentication fail because the pre-shared key on R1 does not match the server's actual key. The correct repair is to first apply 'aaa authentication login default group RADIUS local' to correctly reference the RADIUS server by its name, then set the matching key under 'radius server RADIUS'. Once the key matches, the switch port will transition to authorized state.
What should I do if I get this 200-301 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 200-301 questions on access control and AAA configuration.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Authentication checks who the user is.
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