Which of the following is not part of Day 1 activities?

The process of deploying the Tanium platform involves various activities to ensure the system is properly set up and ready for operation. Among these activities, Day 1 activities typically focus on foundational configurations and initial setups that immediately prepare the environment for use.

Configuring Patch Management is considered a more advanced setup that generally takes place after the initial deployment is complete. It involves establishing policies and processes for keeping software updated and secure, which requires a level of maturity in the Tanium environment that isn't typically achieved on Day 1.

On the other hand, initial configuration of the Tanium platform, client software distribution, and establishing computer groups are fundamental steps that tend to occur early in the deployment process. These tasks are essential to get the Tanium environment functional and allow for immediate data collection and management capabilities among the endpoints.

Therefore, while configuring Patch Management is critical for ongoing maintenance and security, it is not a part of the initial Day 1 activities, making it the correct choice for this question.