Global Accelerator:FAQ about Global Accelerator

If your backend service is deployed on Alibaba Cloud using an Alibaba Cloud account that is different from the account used to activate GA, you can still use GA. Note the following when you configure GA:

• The Alibaba Cloud account that you use to activate GA must have purchased enhanced or premium acceleration bandwidth.

• When you configure the endpoint group, select **Off Alibaba Cloud** for the backend service.

If you use GA to enable the IPv6 Translation Service for a web service, you can use the curl command on an IPv6 client to access the backend IPv4 web service to test if the IPv6 Translation Service is working correctly. Perform the following steps:

1. From an IPv6 client in the acceleration area of the GA instance, open a command-line window.

2. Run the following command to test if the IPv6 client can access the backend IPv4 web service.

   curl -6 -g http://[<Accelerated IP address assigned by GA>]

   The test result shows that the IPv6 client can access the backend IPv4 web service through the accelerated IP address.

The IPv6 Translation Service of GA may not work for several reasons. Check the following items to troubleshoot the issue:

• The GA configuration is incomplete.

  A complete configuration includes at least an acceleration area, a listener (for a standard GA instance), an endpoint group, and an endpoint.

• You can check if your client supports IPv6 Internet access.

  You can run the ping command over IPv6 to test the accelerated IP address. If the test fails, enable the IPv6 feature for the client and ensure that it can access the Internet.

• The DNS record for the domain name is missing or incorrect.

  You can use a command such as dig to check the domain's resolution information. Make sure that an AAAA record that points to the accelerated IPv6 address or a CNAME record that points to the GA CNAME is configured. For more information about how to add a DNS record, see Configure DNS resolution.

• The client's region is not an acceleration area.

  The GA CNAME is region-specific and is affected by the acceleration area configuration. Cross-region access may fail. For example, if the acceleration area includes only regions in the Chinese mainland, the CNAME cannot be resolved from outside the Chinese mainland. To fix this, add an acceleration area outside the Chinese mainland or switch to an AAAA record.

• A security policy or firewall on the origin server is blocking traffic.

  If a security policy is configured, you must allow traffic from the GA public IP addresses.

• Some third-party IPv6 detection websites may provide inaccurate results due to DNS synchronization delays or different detection mechanisms. If a third-party tool reports a failure, use an IPv6 client to directly access the website to verify whether IPv6 is working as expected.

If clients cannot access a backend service after you configure a standard GA instance, check the following items to identify the cause:

• The backend service is not working correctly.

  Try to access your backend service directly. If you cannot access it, check the origin server for issues.

• The client's region is not an acceleration area.

  The GA CNAME is region-specific and is affected by the acceleration area configuration. Cross-region access may fail.

  For example, if the acceleration area includes only regions outside the Chinese mainland (excluding Hong Kong (China)), the CNAME record cannot take effect in the Chinese mainland. As a result, access from clients in the Chinese mainland fails. You can use one of the following solutions:

  • Solution 1: Configure intelligent DNS resolution based on the client's region. Resolve requests from outside the Chinese mainland to the GA CNAME and resolve requests from the Chinese mainland directly to the origin server.

    In this scenario, traffic from outside the Chinese mainland is accelerated by GA. Traffic from the Chinese mainland bypasses GA and connects directly to the origin server, which may result in high latency and packet loss due to carrier and international link limitations.

  • Solution 2: Add an acceleration area in the Chinese mainland to the GA instance and use the default DNS line to resolve all traffic to the GA CNAME.

    GA automatically routes requests to the nearest accelerated IP address based on the client's region. Traffic from outside the Chinese mainland is routed to an accelerated IP address outside the Chinese mainland. Traffic from the Chinese mainland is routed to an accelerated IP address in the Chinese mainland.

    Note: If you add an acceleration area in the Chinese mainland for HTTP or HTTPS services, you must obtain an ICP filing for your custom domain name. Otherwise, access acceleration will fail.

• A security policy on the backend server is blocking traffic.

  Check whether traffic from the public IP address of the endpoint is allowed. You can view the public IP address on the Listener Details tab.

• Check whether the service port for the service domain name is added to the listener of the GA instance.

  For example, if a web application uses both port 80 and port 443, you must add both ports to the GA listener. Otherwise, requests to a port that is not added to the listener will fail.

• Check if the origin server is deployed on Alibaba Cloud. If not, check if the Preserve Client IP feature is enabled.

  The Preserve Client IP feature requires the origin server to support the Proxy Protocol. If your origin server does not support it, access will fail. Disable the Preserve Client IP feature and try to access the service again.

• Traffic exceeds the bandwidth limit of the acceleration area.

  • On the Monitoring Chart tab, check the number of connections and the bandwidth. A DDoS attack may be in progress. For more information, see View the monitoring information of an instance.

  • You can adjust the bandwidth limit of the acceleration area to meet your business requirements. For more information about how to modify the bandwidth limit of an acceleration area, see Modify an acceleration area.

• The client IP address is not in the access control whitelist. Check whether access control is enabled for the GA instance and whether the client IP address is in the access control whitelist.

• Verify that the DNS record for the domain name is configured correctly and resolves to the CNAME or accelerated IP address of the GA instance.

  You can run commands such as dig to check the configuration. For more information, see Configure a CNAME.