Which remediation strategy is not effective for a vulnerability identified by a scanner?

The choice of updating the banner or version number as a remediation strategy is not effective for addressing a vulnerability identified by a scanner because this action does not actually resolve the underlying issue that has been detected. A banner or version number change may provide a superficial response that can mislead users or external observers about the security posture of the system, but it does not rectify the vulnerability itself.

On the other hand, installing a patch is a direct remediation action that addresses the specific vulnerability in the software. Patches are designed to fix known security flaws and are a standard response to vulnerabilities found in the system.

Using a workaround fix involves implementing temporary measures to mitigate the risk of a vulnerability while a permanent solution is being finalized, which can be an effective short-term approach.

Employing an application layer firewall acts as a protective measure that can help filter out potentially harmful traffic or requests aimed at exploiting a vulnerability, thus offering an additional layer of security until the vulnerability can be fully addressed.

Therefore, updating the banner or version number does not contribute to real protection or remediation of the vulnerability in question, making it an ineffective strategy in this context.