Endpoints are pretty much why we have a network. Users utilize endpoints, which includes desktops, laptops, phones, tablets, servers, workstations, and IoT, (internet of things) devices to connect to the network. Endpoints can be hard coded with an ip address or can receive an ip address via dhcp. Endpoints at layer 2 use a mac address, and at layer 3 use an ip address to identify themselves on the network.
You can use endpoints in troubleshooting a network by checking the path between two endpoints. You can use traceroute and ping for example, from one endpoint to another. Telnet is a great tool to check all 7 layers of the OSI model from one endpoint to another endpoint. Generally, endpoints connect to a layer 2 switch, which connects to a router which connect to other routers and there may be firewalls in the path depending on domains of administration. There could be endpoints across the internet, or across an enterprise or just on the same switch. Endpoint to endpoint analysis is a good way to troubleshoot a network.
Endpoints can be points of concern in the case of security. Analysis of endpoints traffic patterns is important because users on endpoints can allow bad traffic, malfunctioning endpoints, bugs, viruses, and bad actors can utilize endpoints to attack a network.
Ken Hagen CCIE #56460 