Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A company is implementing 802.1X port-based authentication on its wired network to control access. The network uses Active Directory for user accounts. Which type of server must be deployed to authenticate clients connecting to the switch ports?
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
A DNS server
DNS resolves domain names to IP addresses but does not authenticate users or devices. It is not part of the 802.1X process.
B
Distractor review
A DHCP server
DHCP assigns IP addresses to clients, but it does not perform authentication. 802.1X typically works before DHCP to ensure only authenticated devices get network access.
C
Best answer
A RADIUS server
RADIUS is the standard protocol for 802.1X authentication. The switch acts as a RADIUS client, sending authentication requests to the RADIUS server, which validates credentials against an identity store (e.g., Active Directory).
D
Distractor review
A Kerberos server
Kerberos is used for authentication in Windows domains but operates at the application layer. 802.1X uses EAP (Extensible Authentication Protocol) over RADIUS, not directly Kerberos. While Active Directory uses Kerberos for domain authentication, the network-level 802.1X authentication is mediated by RADIUS.
Common exam trap
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.
Technical deep dive
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.
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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 network engineer needs to connect two switches located 400 meters apart. The cable run includes high electromagnetic interference from nearby machinery. The engineer decides to use fiber optic cabling. Which transceiver type and fiber combination should be used to ensure the link reaches 400 meters while remaining cost-effective?
Question 2
A network engineer is designing a new switched network and needs to ensure that broadcast traffic from one department does not reach another department's workstations. The engineer plans to use VLANs. Which of the following must be configured on the switches to isolate broadcast domains as intended?
Question 3
A security engineer is configuring a site-to-site VPN between two branch offices. The requirement is to encrypt all traffic between the two networks using IPsec. Which IPsec mode should be used to encrypt the entire IP packet including the original header?
Question 4
A network administrator is connecting two switches to increase bandwidth and provide redundancy. Which technology should be used to combine multiple physical links into a single logical link?
Question 5
A network administrator is experiencing issues where unauthorized devices are offering IP addresses to clients, causing connectivity problems. Which security feature should be enabled on switches to prevent this?
Question 6
A network administrator is troubleshooting a connectivity issue and suspects the problem is related to the physical cabling. At which layer of the OSI model should the administrator begin their investigation?
FAQ
Questions learners often ask
What does this N10-009 question test?
Authentication checks who the user is.
What is the correct answer to this question?
The correct answer is: A RADIUS server — 802.1X relies on RADIUS (Remote Authentication Dial-In User Service) as the authentication server. The switch (authenticator) forwards credentials from the client (supplicant) to the RADIUS server, which checks against an identity store like Active Directory and returns an accept or reject message. RADIUS handles the authentication, authorization, and accounting.
What should I do if I get this N10-009 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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