A vulnerability scan is a process of identifying and assessing known vulnerabilities in a system or network using automated tools or software1 A vulnerability scan can help improve the security posture of a vulnerability management program by detecting and prioritizing potential weaknesses that could be exploited by attackers. To increase the security posture of a vulnerability scan, the following actions can be taken:
Expand the ports being scanned to include all ports: This means scanning all possible ports on a system or network, not just the well-known or commonly used ones. This can help discover more vulnerabilities that may be hidden or overlooked on less frequently used ports.
Increase the scan interval to a number the business will accept without causing service interruption: This means scanning more frequently or regularly, but not so often that it causes performance issues or downtime for the system or network. This can help keep up with new vulnerabilities that may emerge over time and reduce the window of opportunity for attackers.
Enable authentication and perform credentialed scans: This means using login credentials or SSH keys on an asset to get deeper access to its data, processes, configurations, and vulnerabilities2 This can help discover more vulnerabilities that cannot be seen from the network, such as insecure versions of software or poor security permissions.

Explanation
Reducing the attack surface area means limiting the features and functions that are available to an attacker. For example, if I lock all doors to the facility with the exception of one, I have reduced the attack surface. Another term for reducing the attack surface area is system hardening because it involves ensuring that all systems have been hardened to the extent that is possible and still provide functionality