Which technology allows an administrator to remotely manage a fleet of servers?

The management plane is the correct answer because it refers to the layer of management functionalities that allow administrators to control and oversee the operations of a network, including servers, from a remote location. This includes features such as configuration management, monitoring, and automation of tasks across multiple servers. The management plane provides the tools and protocols necessary for remote access and management, enabling efficient and centralized administration of server fleets.

In contrast, other options serve different purposes. A KVM switch enables physical control over multiple servers through keyboard, video, and mouse connections but does not inherently support remote management over a network. A VPN concentrator facilitates secure remote access to a network but lacks specific management functionalities for servers. A bastion host is a secure server designed to act as a gateway and protect the internal network from external threats but does not specifically encompass the management capabilities that the management plane offers.