When a host establishes a Telnet connection with a router interface, the destination address of a frame sent by the host will indeed be the MAC address of the router interface. This is because the frame needs to be delivered to the router, which requires the router's MAC address as the frame's destination address. Furthermore, the destination IP address of a packet will be the IP address of the network interface of the router, since the host is trying to communicate with that specific interface. Therefore, the correct answers are the options indicating the MAC address of the router interface and the IP address of the network interface of the router.