20+ practice questions focused on Layer 2 Authentication And Access Control — one of the most tested topics on the Juniper Networks Enterprise Routing and Switching, Professional (JNCIP-ENT, JN0-650) (JNCIP-ENT) exam. Each question includes a detailed explanation so you learn why the right answer is correct.
Start Layer 2 Authentication And Access Control PracticeYou are troubleshooting an 802.1X deployment on an EX4300 switch. Clients fail to authenticate when using Supplicant-based authentication combined with MAC RADIUS fallback. You notice that the switch does not attempt MAC RADIUS after 802.1X times out. Which configuration error most likely caused this?
Explanation: To fall back to MAC RADIUS when 802.1X fails, the 'authentication-order' statement must explicitly list both dot1x and mac-radius, and the fallback mechanism must be configured properly.
You are implementing MAC RADIUS authentication on an EX4600 switch. You notice that when a device connects, the switch sends the MAC address in the Username attribute (RADIUS attribute 1) with hyphen separators (e.g., aa-bb-cc-dd-ee-ff). Your RADIUS server expects colons (aa:bb:cc:dd:ee:ff). Where must you configure this format change on Junos OS?
Explanation: Junos OS allows modifying the MAC address format sent to the RADIUS server using the 'mac-radius' configuration hierarchy under access profile or interface settings, specifically via the 'mac-питан' or format options.
An EX Series switch is configured with multiple-supplicant mode on an access port connected to an IP phone with a PC daisy-chained behind it. The IP phone authenticates via 802.1X, but the PC uses MAC RADIUS. The phone authenticates successfully and moves to the voice VLAN. However, when the PC boots, it fails authentication because the switch rejects a second supplicant on the same logical port index. Which configuration parameter resolves this issue?
Explanation: In multiple-supplicant mode, the switch allows more than one supplicant (e.g., phone and PC) to authenticate independently on the same port. The correct configuration is 'set protocols dot1x interface ge-0/0/1 supplicant multiple' to enable multiple supplicants, and the port must be in multiple-supplicant mode (not single-secure). This allows the phone to authenticate via 802.1X and the PC to authenticate via MAC RADIUS on the same interface.
You are configuring captive portal on an EX Series switch using J-Web and CLI. Users are redirected to the captive portal page, but after successful authentication, they still cannot access the external network. Inspecting the routing table and firewall filters, what is the most likely reason for this post-authentication restriction?
Explanation: After successful captive portal authentication, the switch must dynamically remove the local firewall filter that redirects traffic to the portal server. If CoA or dynamic VLAN assignment fails, the filter remains active.
An administrator configures 802.1X authentication with local server fallback on an EX Series switch. When the external RADIUS server is unreachable, the switch fails over to the local user database. However, users authenticated via the local database are placed in the default access VLAN instead of the VLAN specified in their local user profile. What is the cause of this behavior?
Explanation: On Junos EX Series switches, the local user database does not support dynamic VLAN assignment via attributes like Tunnel-Type, Tunnel-Medium-Type, or Tunnel-Private-Group-ID. These attributes are typically returned by a RADIUS server to assign a VLAN dynamically. When falling back to the local database, the switch cannot process such attributes because they are not part of the local user profile schema. Therefore, users are placed in the default access VLAN configured on the interface, not a VLAN specified in the local profile. This is a known limitation of local fallback authentication on Junos.
+15 more Layer 2 Authentication And Access Control questions available
Practice all Layer 2 Authentication And Access Control questions1. Baseline your knowledge
Start with 10 questions to gauge your current understanding of Layer 2 Authentication And Access Control. This tells you whether you need a concept refresher or just practice.
2. Review every explanation
For each question — right or wrong — read the full explanation. Understanding why an answer is correct is more valuable than knowing the answer itself.
3. Focus on exam traps
Layer 2 Authentication And Access Control questions on the JNCIP-ENT frequently use trap wording. Look for subtle differences in answers that test your precision, not just general knowledge.
4. Reach 80% consistently
Do repeated sessions until you score 80%+ three times in a row. Then move to mixed-mode practice to test cross-topic recall under realistic conditions.
The exact number varies per candidate. Layer 2 Authentication And Access Control is tested as part of the Juniper Networks Enterprise Routing and Switching, Professional (JNCIP-ENT, JN0-650) (JNCIP-ENT) blueprint. Practicing with targeted Layer 2 Authentication And Access Control questions ensures you can handle any format or difficulty that appears.
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