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Content Delivery Network
Troubleshoot access and slow downloads
Check DNS, HTTPS, caching and the origin in order instead of repeatedly refreshing.
Where to investigate
Go to CDN → Domain management, open the affected domain, and record its status and latest sync time. Configuration offers Sync configuration, Operation logs and Diagnostics and rollback. Review traffic and error trends under Performance monitoring.
Record a reproducible request
Keep the time, full resource path, network, HTTP status and reproducibility. Remove tokens, signatures and personal information from URLs before sharing publicly.
One domain may serve both working and failing resources. Test the exact affected file or endpoint.
Investigate in order
- DNS: confirm that the acceleration domain resolves to its assigned target and no longer uses old records.
- HTTPS: check certificate coverage, validity and chain; determine whether the failure occurs during the TLS handshake.
- Origin: with authorization, check the same resource and origin Host directly. Fix the origin first if it is unavailable.
- Cache: check old and new versions, rules, query parameters and recent purge records.
- Access control: check hotlink protection, IP rules, authorization expiry and application permissions.
What status codes suggest
| Issue | Check first |
|---|---|
| 403 | Access controls, URL authorization and origin permissions; this does not necessarily mean a ban |
| 404 | Origin path, case, origin Host and cached old error responses |
| 5xx | Origin connectivity, timeouts, origin DNS, HTTPS origin connections and server errors |
| Old file version | Origin replacement, cache rules, purge scope and browser cache |
| Slow downloads | Client network, cache hit rate, origin response, large-file origin fetching and response rate limits |
Large files and Range requests to the origin
Range requests retrieve part of a file. Partial origin fetching can avoid retrieving an entire large file for one segment. The origin must correctly support Range.
CDN Range fetching and a visitor sending Range requests are separate behaviors. The current origin settings page has no standalone Range switch; confirm the domain's capabilities before requesting a change.
Status-code or hit-rate statistics provide clues, but a single drop does not establish an attack. Use logs and real responses to guide action.
Reproduce one file request
Replace the example domain and path below with your own public test resource. The returned CNAME should match Domain management. Headers help verify status and redirects but do not prove file completeness.
nslookup -type=CNAME download.example.com
curl -I https://download.example.com/releases/demo.zipExample domains and paths are illustrative. Replace them with real resources you are authorized to use.
Do not paste private signed or token-bearing URLs into public tickets. If the origin does not support HEAD, reproduce the actual request method.
Verify again after fixing
Retest the original file path, network and client. Compare status, content and version after each change so that simultaneous changes do not hide the cause.
If a recent setting caused the issue, use Diagnostics and rollback to restore an older version as a draft. Review it, then save the affected module. Restoring a draft alone does not update remote configuration.