HP HPE6-A78 Exam With Confidence Using Practice Dumps

The scenario involves troubleshooting an 802.1X authentication issue on HPE Aruba Networking switches (likely AOS-CX switches) that use a cluster of HPE Aruba Networking ClearPass Policy Manager (CPPM) servers as the RADIUS server. The switches show Access-Rejects in their statistics, indicating that CPPM is receiving and processing the authentication requests but rejecting them. However, the records for these Access-Rejects are not visible in CPPM Access Tracker.

Access Tracker: Access Tracker (Monitoring > Live Monitoring > Access Tracker) in CPPM logs all authentication attempts, including successful (Access-Accept) and failed (Access-Reject) requests. If an Access-Reject is not visible in Access Tracker, it suggests that the request was processed at a lower level and not logged in Access Tracker, or there is a visibility issue (e.g., filtering, clustering).

Option A, "Go to the CPPM Event Viewer, because this is where RADIUS Access Rejects are stored," is correct. The Event Viewer (Monitoring > Event Viewer) in CPPM logs system-level events, including RADIUS-related events that might not appear in Access Tracker. For example, if the Access-Reject is due to a configuration issue (e.g., the switch’s IP address is not recognized as a Network Access Device, NAD, or the shared secret is incorrect), the request may be rejected before it is logged in Access Tracker, and the Event Viewer will capture this event (e.g., "RADIUS authentication attempt from unknown NAD"). Since the switches confirm that CPPM is sending Access-Rejects, the Event Viewer is a good place to look for more details.

Option B, "Verify that you are logged in to the CPPM UI with read-write, not read-only, access," is incorrect. Access Tracker visibility is not dependent on read-write vs. read-only access. Both types of accounts can view Access Tracker records, though read-only accounts cannot modify configurations. The issue is that the records are not appearing, not that the user lacks permission to see them.

Option C, "Make sure that CPPM cluster settings are configured to show Access-Rejects," is incorrect. In a CPPM cluster, Access Tracker records are synchronized across nodes, and there is no specific cluster setting to "show Access-Rejects." Access Tracker logs all authentication attempts by default, unless filtered out (e.g., by time range or search criteria), but the issue here is that the records are not appearing at all.

Option D, "Click Edit in Access Viewer and make sure that the correct servers are selected," is incorrect. Access Tracker (not "Access Viewer") does not have an "Edit" option to select servers. In a CPPM cluster, Access Tracker shows records from all nodes by default, and the user can filter by time, NAD, or other criteria, but the absence of records suggests a deeper issue (e.g., the request was rejected before logging in Access Tracker).

The HPE Aruba Networking ClearPass Policy Manager 6.11 User Guide states:

"If an Access-Reject is not visible in Access Tracker, it may indicate that the RADIUS request was rejected at a low level before being logged. The Event Viewer (Monitoring > Event Viewer) logs system-level events, including RADIUS Access-Rejects that do not appear in Access Tracker. For example, if the request is rejected due to an unknown NAD or shared secret mismatch, the Event Viewer will log an event like ‘RADIUS authentication attempt from unknown NAD,’ providing insight into the rejection." (Page 301, Troubleshooting RADIUS Issues Section)

Additionally, the HPE Aruba Networking AOS-CX 10.12 Security Guide notes:

"When troubleshooting 802.1X authentication issues, if the switch logs show Access-Rejects from the RADIUS server (e.g., ClearPass) but the records are not visible in Access Tracker, check the RADIUS server’s system logs. In ClearPass, the Event Viewer logs RADIUS Access-Rejects that may not appear in Access Tracker, such as those caused by NAD configuration issues." (Page 150, Troubleshooting 802.1X Authentication Section)

Without the integration of Aruba ClearPass or other advanced network access control solutions, ArubaOS devices (controllers and Instant APs) are able to use DHCP fingerprinting to assign roles to clients. This method allows the devices to identify the type of client devices connecting to the network based on the DHCP requests they send. While this is a more basic form of endpoint classification compared to the capabilities provided by ClearPass, it still enables some level of access control based on device type. This functionality and its limitations are described in Aruba's product documentation for ArubaOS devices, highlighting the benefits of integrating a full-featured solution like ClearPass for more granular and powerful endpoint classification capabilities.

The scenario involves AOS-CX switches in a two-tier topology with Switch-1 as the core switch (default router) on VLAN 100 and Switch-2 as an access layer switch with VLANs 15 and 25, where end-user devices connect. The goal is to protect against exploits from untrusted end-user devices, such as DHCP spoofing or ARP poisoning attacks, which are common threats in access layer networks.

DHCP Snooping: This feature protects against rogue DHCP servers by filtering DHCP messages. It should be enabled on the access layer switch (Switch-2) where end-user devices connect, specifically on the VLANs where these devices reside (VLANs 15 and 25). DHCP snooping builds a binding table of legitimate IP-to-MAC mappings, which can be used by other features like ARP inspection.

ARP Inspection: This feature prevents ARP poisoning attacks by validating ARP packets against the DHCP snooping binding table. It should also be enabled on the access layer switch (Switch-2) on VLANs 15 and 25, where untrusted devices are connected.

Option B, "On Switch-2, enable DHCP snooping globally and on VLANs 15 and 25. Later, enable ARP inspection on the same VLANs," is correct. DHCP snooping must be enabled first to build the binding table, and then ARP inspection can use this table to validate ARP packets. This configuration should be applied on Switch-2, the access layer switch, because that’s where untrusted end-user devices connect.

Option A, "On Switch-1, enable ARP inspection on VLAN 100 and DHCP snooping on VLANs 15 and 25," is incorrect. Switch-1 is the core switch and does not directly connect to end-user devices on VLANs 15 and 25. DHCP snooping and ARP inspection should be enabled on the access layer switch (Switch-2) where the devices reside. Additionally, enabling ARP inspection on VLAN 100 (where the DHCP server is) is unnecessary since the DHCP server is a trusted device.

Option C, "On Switch-2, enable BPDU filtering on all edge ports in order to prevent eavesdropping attacks by untrusted devices," is incorrect. BPDU filtering is used to prevent spanning tree protocol (STP) attacks by blocking BPDUs on edge ports, but it does not protect against eavesdropping or other exploits like DHCP spoofing or ARP poisoning, which are more relevant in this context.

Option D, "On Switch-1, enable DHCP snooping on VLAN 100 and ARP inspection on VLANs 15 and 25," is incorrect for the same reason as Option A. Switch-1 is not the appropriate place to enable these features since it’s not directly connected to the untrusted devices on VLANs 15 and 25.

The HPE Aruba Networking AOS-CX 10.12 Security Guide states:

"DHCP snooping should be enabled on access layer switches where untrusted end-user devices connect. It must be enabled globally and on the specific VLANs where the devices reside (e.g., dhcp-snooping vlan 15,25). This feature builds a binding table of IP-to-MAC mappings, which can be used by Dynamic ARP Inspection (DAI) to prevent ARP poisoning attacks. DAI should also be enabled on the same VLANs (e.g., ip arp inspection vlan 15,25) after DHCP snooping is configured, ensuring that ARP packets are validated against the DHCP snooping binding table." (Page 145, DHCP Snooping and ARP Inspection Section)

Additionally, the guide notes:

"Dynamic ARP Inspection (DAI) and DHCP snooping are typically configured on access layer switches to protect against exploits from untrusted devices, such as DHCP spoofing and ARP poisoning. These features should be applied to the VLANs where end-user devices connect, not on core switches unless those VLANs are directly connected to untrusted devices." (Page 146, Best Practices Section)