Any or combination of the following:
- Your site is unreachable via Incapsula
- Site visitors experiencing “time out”
- Site visitors constantly receive an error page when accessing the site
- Your event log is showing “server is unreachable”
- Site visitors experience intermittent connectivity issues
- see an Incapsula page with "Error code 20"
Upon completion of the DNS changes, as outlined by Incapsula, you are effectively directing all of your traffic via Incapsula’s network of proxy servers (Incapsula proxies). Incapsula proxies access your servers directly, and then serve content to the site visitors. Requests to your servers are therefore all coming from a limited range of Incapsula IP addresses. This may result in being classified as attack traffic by various traffic limiting mechanisms and denying Incapsula from accessing your servers.
Possible root cause:
- Incapsula’s proxies are unable to connect to your servers.
- There is a firewall or rate limiting mechanism that is blocking access to your servers.
- There is a software package installed on your servers that is restricting access (for example: Apache servers have various modules that block requests: mod_deflate, mod_cband, mod_throttle, mod_bwlimited as well as others. The modules are intended to protect the server from high flow of traffic from a single source.
- In the case of a firewall or rate limiting mechanism that is blocking access, please contact your hosting provider to whitelist Incapsula’s IP ranges listed in this article.
- In the case of a software package that is limiting the traffic, please adjust it to allow unrestricted traffic from Incapsula’s IP ranges listed in this article.
For more information about Incapsula error pages: Link