This article explains why a Framed Web Forward may not mask the destination URL and how to determine whether the issue originates from UltraDNS web forwarding or the destination web server.
Symptom
A host configured with a Framed Web Forward does not mask the URL, and the destination URL becomes visible in the browser.
How to Test
- Open Firefox.
- If not already installed, install Live HTTP Headers.
- Click Tools, then click Live HTTP Headers.
- Ensure Capture is checked.
- Enter the affected hostname in the browser.
- Review the captured headers and confirm whether 500, 501, 502, or 503 errors appear with the unmasked URL as referrer.
Root Cause
Consecutive 500-level errors with the unmasked URL as referrer indicate that the destination web server is returning server-side errors. When the destination server returns these errors, URL masking cannot function properly.
Resolution
- Capture the HTTP headers using the steps above.
- Provide the captured HTTP headers to your web hosting provider.
- Work with your hosting provider to resolve the 500-level errors.
Verification
- Confirm the destination web server no longer returns 500-level errors.
- Retest the Framed Web Forward and confirm the URL remains masked as expected.