Correct Answer: D
Comprehensive and Detailed in Depth Explanation:
After initializing Vault, the default authentication method isTokens, specifically the root token. The HashiCorp Vault documentation states: "After initializing, Vault provides the user the root token, which is the only way to log in to Vault in order to configure additional auth methods." This root token is generated during initialization and serves as the initial means of authentication until other methods are configured.
The documentation further explains under the "Token Authentication" section: "Tokens are the core method for authentication within Vault. Upon initialization, a root token is created which can be used to configure Vault further."TLS certificates,GitHub,AppRole, andUserpassrequire additional setup, and there's no defaultAdmin accountmethod. Thus, D (Tokens) is correct.
Reference:
HashiCorp Vault Documentation - Token Authentication