To automate the provisioning of Cisco ACI objects using Terraform while ensuring that APIC counts the authentication login requests against the threshold to avoid a DOS attack, signature-based authentication should be used. This method involves obtaining an authentication token from Cisco APIC, which will use the token to authenticate. However, APIC counts these authentication requests and applies a threshold to prevent DOS attacks. After too many attempts, the user ID and password authentication method may fail as the threshold is exceeded. To circumvent this issue, signature-based authentication is recommended, where a signature is calculated using a private key and passed with the request. This signature is then used to authenticate the user without being counted against the threshold, thus avoiding the risk of exceeding it and failing authentication.
References: The information is based on the Terraform documentation provided by CiscoDevNet