What Are the Causes of an API Calling Failure?

API calling failures are classified into three types: failure of API calling in the same VPC, failure of API calling between different VPCs, and failure of API calling through a public network.

• If the API fails to be called in the VPC, check whether the domain name is the same as that automatically allocated by the API. If the domain name is different from that automatically allocated by the API, the API fails to be called.
• If APIs fail to be called between VPCs, check whether the two VPCs are connected. If the two VPCs are not connected, you can establish VPC peering connections to enable communication between the two VPCs.
• If APIs fail to be called through a public network, the possible causes are as follows:
  • The API is not bound to an EIP. As a result, the API lacks a valid address for public network access, and therefore the API fails to be called through a public network.
  • The inbound rule is incorrectly configured. As a result, the API fails to be called through a public network.
  • The request header "host: Group domain name" is not added during API calling. As a result, the API fails to be called through a public network. The API can be called as long as the message header is added.