The best audit evidence that a firewall is configured in compliance with the organization's security policy is to review the rule base. The rule base is a set of rules that defines the criteria for allowing or denying network traffic through the firewall. By reviewing the rule base, the auditor can verify if the firewall configuration matches the security policy requirements and objectives. Analyzing how the configuration changes are performed, analyzing log files, and performing penetration testingare useful audit techniques, but they do not provide direct evidence of the firewall configuration compliance. References: CISA Review Manual (Digital Version)1, page 383.