The administrator observes IP SLA jitter monitoring results spiking to 100% when monitoring UCC sessions. This indicates either extremely severe network jitter or, more likely, a problem with the IP SLA operation or measurement itself on the AOS-CX switch.  

IP SLA & Jitter: IP SLA measures jitter by analyzing the inter-packet delay variation of probe packets. Accurate measurements depend on the switch generating and processing these probes consistently.

Factors Affecting IP SLA Accuracy:

Switch Resource Contention: If the switch's CPU or memory is heavily utilized, the operating system might not schedule the IP SLA process promptly. This can lead to inconsistent generation or processing of probe packets, causing highly inaccurate measurements, including extreme jitter values like 100%.

Control Plane Policing (CoPP): IP SLA packets are control plane traffic. If CoPP policies are too restrictive, they might drop or delay IP SLA probes, skewing results.

Network Path Issues: Actual severe jitter on the network path would also cause high readings, but 100% spikes often suggest measurement error first.

Troubleshooting Steps: When encountering unexpectedly high or erratic IP SLA results, the first step is often to rule out issues with the monitoring device itself.

Analysis of Options:

A. memory and processor usage: Checking the switch's resource utilization is crucial. High CPU/memory load can directly impact the timing accuracy of IP SLA operations.

B. source IP and source port combination: Unlikely to cause 100% jitter spikes unless fundamentally misconfigured causing probe failure.

C. number of NAE agents: NAE agents consume resources, but checking overall CPU/memory (A) is more direct.

D. CoPP settings: A valid concern, as CoPP affects control plane traffic. However, checking overall system load (A) is typically a primary check before delving into specific policies like CoPP.

Conclusion: High memory and processor usage (Option A) on the switch running the IP SLA operation is a common cause for inaccurate timing and resulting erroneous jitter measurements. This should be checked first to ensure the monitoring platform itself is functioning correctly.

The question involves an EAP timeout in HPE Aruba Networking ClearPass Access Tracker during an 802.1X authentication attempt, with the task of identifying a possible cause.

Analysis of Options:

Option A: Incorrect. A client certificate trust issue would cause a different error, not an EAP timeout.

Option B: Incorrect. An expired client certificate would result in an authentication failure, not a timeout.

Option C: Incorrect. If the client sees an expired RADIUS server certificate, it would reject it, but this typically causes a trust error, not a timeout.

Option D: Correct. If the client does not trust the RADIUS server’s certificate (e.g., missing CA certificate or untrusted issuer), it may fail to proceed with the EAP handshake, leading to an EAP timeout.

Why Option D is Correct: In 802.1X authentication with EAP (e.g., EAP-TLS or EAP-PEAP), the client must trust the RADIUS server’s certificate to establish a secure TLS tunnel. If the client’s trust store lacks the Certificate Authority (CA) certificate or the server’s certificate is untrusted (e.g., self-signed without proper installation), the client aborts the EAP handshake, resulting in an EAP timeout logged in ClearPass. This is a common issue in 802.1X deployments and can be resolved by ensuring the client has the correct CA certificate or by using a trusted server certificate, as per HPE Aruba Networking’s security guidelines.

Relevance to Certification Objectives:

Authentication/Authorization (9%): Troubleshooting 802.1X and ClearPass authentication issues.

Security (10%): Diagnosing wired 802.1X with EAP-TLS failures.

Troubleshooting (10%): Resolving authentication timeouts in campus networks.

The ClearPass Event Viewer message "RADIUS authentication attempt from unknown NAD (10.10.1.10:1812)" indicates that ClearPass received a RADIUS request from the IP address 10.10.1.10, but this IP is not configured as a trusted Network Access Device (NAD) in ClearPass's network device list, or the shared secret doesn't match. The first step in troubleshooting on the switch side is to verify which source IP address the switch is actually using to send these RADIUS requests.

RADIUS Source IP: AOS-CX switches can be configured to use a specific source IP address for RADIUS packets, often using the ip source-interface radius [vrf < vrf-name > ] command. This is important if the switch has multiple IP interfaces or uses VRFs.

Analysis of Commands:

A. show ip source-interface radius: This command directly displays the configured source interface and IP address used for RADIUS communications, allowing comparison with the IP configured in ClearPass.  

B. show aaa authentication-server radius: Shows server group configuration, not the source IP used by the switch.

C. show radius-server shared-secret: Not a standard command; secrets are usually masked in other commands.

D. show radius-server detail: Shows configured RADIUS server details but doesn't explicitly show the source IP the switch is using to originate packets.

Conclusion: To identify why ClearPass sees requests from an "unknown NAD" IP (10.10.1.10), the first step on the switch is to confirm which source IP it's using. show ip source-interface radius provides this crucial information.