An administrator needs to connect a router in one building to a router in another using Ethernet. Each router is connected to a managed switch and the switches are connected to each other via a fiber line. Which of the following should be configured to prevent unauthorized devices from connecting to the network?
A. Configure each port on the switches to use the same VLAN other than the default one B. Enable VTP on both switches and set to the same domain C. Configure only one of the routers to run DHCP services D. Implement port security on the switches
Answer: D
Explanation: Port security in IT can mean several things: The physical control of all connection points, such as RJ-45 wall jacks or device ports, so that no unauthorized users or unauthorized devices can attempt to connect into an open port. The management of TCP and User Datagram Protocol (UDP) ports. If a service is active and assigned to a port, then that port is open. All the other 65,535 ports (of TCP or UDP) are closed if a service isn’t actively using them. Port knocking is a security system in which all ports on a system appear closed. However, if the client sends packets to a specific set of ports in a certain order, a bit like a secret knock, then the desired service port becomes open and allows the client software to connect to the service.