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Slow content delivery troubleshooting

Check the origin for errors or misconfigurations that can reduce delivery speed. Contact the hosting provider or server administrator if origin-side analysis is needed.

CDN and origin speed comparison

Compare the same static file under consistent test conditions so differences reflect the delivery path rather than the client, location, or object.

  1. 1

    Select a static file

    Select one static file that is available through both the CDN URL and the origin URL.

  2. 2

    Test CDN delivery

    From the test client and location, request the file through the CDN:

    wget -S -O /dev/null https://cdn.example.com/files/test.jpg

    Confirm that the response includes the Cache: HIT header, which indicates that the file was served from the CDN edge cache.

  3. 3

    Test origin delivery

    From the same client and location, request the same file directly from the origin:

    wget -S -O /dev/null https://origin.example.com/files/test.jpg
  4. 4

    Repeat and compare

    Repeat both tests to reduce the effect of temporary network variation, then compare the transfer results. If CDN delivery remains slower, review the settings below.

CDN resource settings

Confirm that a VPN or proxy is not in use, because either can route traffic through a suboptimal edge and reduce delivery speed.

Check the cache hit ratio in the Customer Portal:

  1. 1

    Open CDN

    In the CDB Technical Web Portal, navigate to CDN.

  2. 2

    Open Statistics

    Expand Reports and select Statistics.

  3. 3

    Select the cache report

    Select Cache hit ratio.

A low cache hit ratio means more requests reach the origin, which can increase delivery time.

For slow delivery of large files, select one of these alternatives for the same CDN resource or rule:

  • The large file delivery settings enable Large files delivery optimization, which is incompatible with Fetch compressed, Gzip, and Brotli
  • Gzip and Brotli reduce transfer size for compressible content and must be used without Large files delivery optimization in the same resource or rule

Diagnostic information for technical support

If delivery speed is still too low after reviewing settings, contact CDB Support and include:

  • The file URL
  • The JSON output from https://gcore.com/.well-known/cdn-debug/json (open the URL and copy the full response)
  • Results from the CDB speed test — click Run test, then save the result
  • wget -S output for both the CDN and origin URLs
  • A HAR file exported while loading the file or page. In browser DevTools, open the Network panel, reload the page, and select Export HAR