What is the first step when adding a computer to a domain?

When adding a computer to a domain, the initial step is to log into the computer with administrative credentials. This is crucial because administrative access is required to modify system settings and configure the computer to join the domain. Without these credentials, essential actions such as accessing network settings or system properties would be restricted, preventing the user from proceeding with the necessary configurations for domain integration.

Having logged in as an administrator, the individual can then navigate to the appropriate system properties where they can input the domain information and complete the joining process. This step ensures that the user has the necessary permissions to make changes that affect network connectivity and domain membership, setting a solid foundation for all subsequent actions involved in the domain addition.