Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A switchport is configured for 802.1X authentication. What is the usual role of the RADIUS server in that design?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
It provides Layer 2 trunk negotiation for the supplicant.
RADIUS does not negotiate switchport trunking.
B
Best answer
It validates authentication credentials for the supplicant.
Correct. The RADIUS server performs centralized AAA decisions.
C
Distractor review
It replaces the need for DHCP on the access layer.
RADIUS and DHCP have different functions.
D
Distractor review
It generates ARP replies on behalf of the default gateway.
RADIUS does not perform ARP gateway functions.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is assuming the RADIUS server handles functions beyond authentication, such as DHCP IP address assignment or ARP gateway replies. Candidates might mistakenly believe that RADIUS negotiates switchport trunking or manages Layer 2 connectivity, which it does not. This confusion often arises because RADIUS is involved in network access control but does not replace other network services. Misunderstanding these roles can lead to selecting incorrect options that describe unrelated network functions, causing errors in the exam.
Technical deep dive
How to think about this question
802.1X is a network access control protocol that provides port-based authentication to devices attempting to connect to a LAN or WLAN. In this design, the switchport acts as the authenticator, controlling access to the network port. The device connecting to the switchport, known as the supplicant, must provide valid credentials before gaining access. The RADIUS server plays a critical role by acting as the authentication server that centrally validates these credentials, ensuring only authorized users or devices can access the network. When a supplicant attempts to connect, the switchport forwards the authentication request to the RADIUS server using the RADIUS protocol. The server then checks the credentials against its database or an external identity source. If the credentials are valid, the RADIUS server sends an acceptance message back to the switch, which then enables network access on the port. If the credentials are invalid, access is denied. This centralized AAA (Authentication, Authorization, and Accounting) model enhances security and simplifies management in Cisco networks. A common exam trap is confusing the role of the RADIUS server with other network functions such as DHCP or ARP. The RADIUS server does not provide IP address assignment or gateway functions; it strictly handles authentication requests. Practically, this means that even if the RADIUS server is operational, devices still require DHCP for IP addressing and proper network communication. Understanding this separation of duties is crucial for correctly answering questions about 802.1X and RADIUS in the CCNA exam context.
KKey Concepts to Remember
- The RADIUS server validates authentication credentials for devices or users attempting to access a switchport configured with 802.1X authentication.
- 802.1X uses the switchport as an authenticator that forwards supplicant credentials to the RADIUS server for centralized AAA decisions.
- The RADIUS server does not perform Layer 2 trunk negotiation; this function is handled by protocols like DTP or manual switchport configuration.
- RADIUS and DHCP serve distinct purposes; RADIUS handles authentication while DHCP assigns IP addresses to network devices.
- The RADIUS server does not generate ARP replies or perform gateway functions; these are handled by routers or Layer 3 devices.
- In Cisco networks, 802.1X with RADIUS enhances security by preventing unauthorized network access at the port level.
- The switchport remains in a blocked state until the RADIUS server approves the supplicant’s credentials, enforcing network access control.
- Centralized authentication via RADIUS simplifies management and auditing of network access in enterprise environments.
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
The RADIUS server validates authentication credentials for devices or users attempting to access a switchport configured with 802.1X authentication.
What is the correct answer to this question?
The correct answer is: It validates authentication credentials for the supplicant. — The switch acts as the authenticator and forwards authentication requests to the RADIUS server, which validates the user or device credentials.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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