Why Am I Seeing the Message "Backend domain name resolution failed" When a Backend Service Is Called?

An error message indicating a domain name resolution failure is displayed when the backend service is called, although private domain name resolution is completed for the VPC where the API gateway is located.

Possible Cause

The VPC of the API gateway is isolated from that of the backend service. Private domain names can be resolved only for the VPC of the backend service.

Solution

• Method 1: When creating an API, set Backend Address to a public network domain name.
• Method 2: When creating an API, do not use a VPC channel (load balance channel). Instead, set Backend Address to the backend service IP address, and add a constant parameter to specify the Host field in the header.

• Method 3: When creating an API, specify a VPC channel (load balance channel).
  1. Create a VPC channel (load balance channel).

  2. Add the backend service address.

  3. When creating an API, select the VPC channel (load balance channel) and configure a custom header.