A network device can include a tuner configured to receive audio and video data of at least one broadcast program, a network interface configured to receive at least one thumbnail image corresponding the at least one broadcast program, a user interface configured to receive a first command for executing an electronic program guide from a remote controller, and a controller configured to output a signal for displaying the electronic program guide in response to the first command. Also, the electronic program guide can include the at least one thumbnail image within a designated time zone.