Troubleshooting intermittent performance issues is a core component of theDesigning and Implementing Enterprise Network Assurance (300-445 ENNA)curriculum. When a transaction test using Basic Authentication fails randomly, the engineer must employ a multi-layered diagnostic approach to determine if the fault lies with the credentials, the network path, or the application server.

The first step is toverify the correctness of credentials(Option B). Because Basic Authentication encodes credentials in the header, any change in user permissions or account lockouts will trigger immediate failures. Performing manual logins from various geographical locations helps rule out location-based access control lists (ACLs) or regional IdP sync issues.

The most data-rich diagnostic step is toanalyze the ThousandEyes waterfall charts and HTTP response codes(Option C). The waterfall view allows the engineer to see if the failure happens during the initial 401 Unauthorized challenge or after the credentials are sent. If the charts show high "Wait Time" or 5xx errors, the issue is likely server-side latency or instability. If the "Connect Time" is high, the problem may be network-layer congestion.

Finally, if the telemetry indicates that the network path is healthy but the server is intermittently returning errors or timing out, the engineer shouldcontact the web application vendor(Option D). Providing the vendor with the specific ThousandEyes "Share Link" allows them to see the exact same packet-level and browser-level data, proving that the issue is not with the client's network but with the server-side infrastructure. Disabling authentication (Option A) is not a valid troubleshooting step for a test designed specifically to monitor an authenticated workflow.