Ensuring the Tableau Server service account has the appropriate SPNs set for the server's fully qualified domain name (FQDN) Setting the correct SPNs for the Tableau Server service account is crucial for Kerberos authentication. SPNs should be associated with the service account running Tableau Server and must match the server's FQDN. This enables Kerberos to correctly identify and authenticate the server in a network, ensuring secure communication. Option A is incorrect because SPNs are set for the service account running the server, not for each individual user account in Tableau Server. Option C is incorrect as SPNs are not directly tied to IP addresses but to service accounts and the FQDN of the server. Option D is incorrect because while SSL encryption is important for security, it is not directly related to the configuration of SPNs for Kerberos authentication.