What does an authentication failure typically indicate in a network environment?

An authentication failure in a network environment primarily indicates an inability to verify identity. This situation arises when a device attempts to connect to a network but fails to provide valid credentials or the proper security protocol required to gain access. The authentication process is crucial for maintaining network security, ensuring that only authorized users and devices can access network resources.

When authentication fails, it often means that the user or device has not presented the correct username and password, or there may be issues with the authentication server that prevent it from validating the credentials. This outcome directly impacts the security of the network by potentially blocking unauthorized access.

The other options describe different network issues. For instance, improper lease with DHCP refers to problems with IP address assignment, device overload indicates that a system is overwhelmed with requests, and connectivity issues pertain to general problems with network connections. While these can be serious concerns, they do not specifically relate to the process of authentication, which is focused on identity verification.