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    Tair (Redis® OSS-Compatible):Troubleshoot connection issues caused by failed domain name resolution

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    Tair (Redis® OSS-Compatible):Troubleshoot connection issues caused by failed domain name resolution

    Last Updated:Feb 04, 2026

    When you use an endpoint to connect to a Tair (or Redis Open-Source Edition) instance, an issue with the Domain Name System (DNS) service can prevent an Elastic Compute Service (ECS) instance from resolving the endpoint. This interrupts the network connection between the ECS and Tair instances. This topic describes how to resolve such issues.

    Cause

    Connection issues between an ECS instance and a Tair instance can have many causes. If you receive one of the following error messages, it indicates that the hostname or endpoint cannot be resolved. In this case, check the domain name and the DNS server settings.

    • Name or service not known

    • UnknownHostException

    • failed to connect: r-***************.redis.rds.aliyuncs.com could not be resolved

    Procedure

    The following procedure uses a Linux environment as an example.

    1. Verify that the Tair endpoint specified in your service code is correct.

      Note

      You can view the Tair endpoint on the instance details page in the Tair console. The endpoint is in the Endpoint section, as shown in the following figure.

      Figure 1. View endpoint查看连接地址

    2. Confirm that the correct DNS server is configured on the ECS instance. For more information, see An ECS instance that runs Linux fails to resolve domain names.

    3. Optional: If the previous steps do not resolve the issue, you can use the following temporary solution.

      Add the domain name and IP address mapping for the Tair instance to the /etc/hosts file to ensure that the domain name can be resolved. Then, see Troubleshoot Tair connection issues to rule out other causes of the connection issue.

      Important

      The method for editing the /etc/hosts file is similar to editing the resolv.conf file. However, modifying the /etc/hosts file is only a temporary solution that becomes invalid if the IP address of the Tair instance changes.