What is a common drawback of relying solely on local usernames?

Relying solely on local usernames does indeed present the issue of scalability. In environments where multiple devices need to be managed, the use of local usernames can become cumbersome. Each device would require its own set of usernames and passwords, making it difficult to manage and potentially leading to inconsistent access controls.

As the network grows, adding new users or managing access for existing users can become increasingly complex and time-consuming. This method does not easily accommodate large numbers of users or the dynamic changes that occur in organizational structure, leaving administrators with a challenge in maintaining access rights effectively across the entire network.

In contrast, centralized authentication methods, such as those provided by directory services, allow for easier user management and can scale as needed, thereby enhancing both security and efficiency in larger network environments.