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    :Troubleshoot unreachable websites after using Alibaba Cloud Content Delivery Network Acceleration

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    :Troubleshoot unreachable websites after using Alibaba Cloud Content Delivery Network Acceleration

    Last Updated:Jun 25, 2023

    Description

    This topic describes how to troubleshoot unreachable websites after Alibaba Cloud CDN acceleration is used.

    References

    After you use Alibaba Cloud Content Delivery Network acceleration, if you return 304, 403, 404, 503, and 504 status code, you can perform the following operations:

    If the problem cannot be solved through the preceding operations, you can perform the following operations to troubleshoot the problem. This topic uses a www.example.com accelerated domain name as an example.

    1. For more information about checking whether Alibaba Cloud Content Delivery Network access exceptions are Alibaba Cloud Content Delivery Network node problems or origin problems, see How to troubleshoot whether Alibaba Cloud Content Delivery Network access exceptions are Alibaba Cloud Content Delivery Network node problems or origin problems.
      • If the origin server access exception occurs, check the origin service.
      • If a Alibaba Cloud Content Delivery Network exception occurs, proceed to the next troubleshooting step.
    2. Check whether the domain name has been Alibaba Cloud Content Delivery Network accelerated.
      1. Run the ping command to test the network connectivity with the accelerated domain name. If the response is the same as the CNAME value of the accelerated domain name in the Alibaba Cloud Content Delivery Network console, the Alibaba Cloud Content Delivery Network acceleration has taken effect.
      2. If the IP address is still the origin server IP address of the domain name, the domain name acceleration does not take effect. For more information, see Domain name acceleration configuration.
    3. Check whether back-to-origin is normal. If you have determined to resolve to the Alibaba Cloud Content Delivery Network through step 1, you only need to access a URL under the domain name in the browser to know the access effect after Alibaba Cloud Content Delivery Network acceleration.
      Modify the hosts file. For more information about how to configure a host, see How to bind a domain name to a host. After adding similar 192.168.0.1 www.example.com entries to save, clear the browser cache and reopen it. If you access it again, it is the back-to-origin access effect.
      Description: 192.168.0.1 is the origin IP address and www.example.com is the domain name to be checked.  
      • If the access is still abnormal, indicating that the origin site access is abnormal, directly check the origin site service.
      • If the back-to-origin is normal and abnormal after Alibaba Cloud Content Delivery Network, proceed to the troubleshooting operation in the next step.


    4. Check whether the Alibaba Cloud Content Delivery Network configuration is correct. Log on to the Alibaba Cloud Content Delivery Network console, check the configuration of the domain name by www.example.com this domain name, and check whether the CNAME matches correctly.
      Note: The origin server on the Alibaba Cloud Content Delivery Network console is the IP address of the corresponding origin server. Whether you set an IP address or a domain name here, it will be resolved to the corresponding domain name for back-to-origin. The site corresponding to the origin site is determined by returning to the origin host, so returning to the origin host must correspond to the site of the origin external service.
      The CNAME generated on the platform by the www.example.com domain name can only be used by www.example.com domain names and cannot be provided to other domain names. For example, the following example shows the incorrect use of a img.example.com domain name. The img.example.com CNAME must start with img.example.com.
    5. Check the configurations of the origin server. Log on to the Alibaba Cloud Content Delivery Network console and check whether the configuration of the origin server is the origin server of the domain name in the basic configuration of the domain name. If not, change it to the corresponding server IP address.
    6. Check the security policies of the origin server. If all the above configurations are correct, the Alibaba Cloud Content Delivery Network has been properly configured. Check whether some security policies, such as firewalls, are configured on the origin server. If a security policy is configured, check whether there are IP blocking records for the following four IP segments. If there are blocking records, add a whitelist. 
      140.205.127.0/25 140.205.253.128/25 139.196.128.128/25 101.200.101.0/25

    7. Check whether the IP address corresponding to the accelerated domain name is added to the IP blacklist:

      1. Log on to the Alibaba Cloud Content Delivery Network console.
      2. In the left-side navigation pane, click Domain Names.
      3. On the Domain Names tab, find the target domain name and click Manage.
      4. In the left-side navigation pane of the specified domain name, click Access Control.
      5. In the IP Blacklist or Whitelist section, click Modify.
      6. In the Blacklist Rule section, delete the IP address corresponding to the accelerated domain name.
      7. Click OK to complete the configuration.

    References

    Applicable scope

    • CDN