• 15. (1 pt) Consider 4 nodes with MAC addresses A, B, C, and D connected to interfaces 1, 2, 3, and 4 respectively of a switch, according to a star topology. Assume prior to event 1, the switch table is empty (all entries are blank). Suppose event 1 happens: B sends a frame to D. List all the interface(s) to which the switch forwards the frame. List only the interface numbers, separated by commas, by order of increasing number. Do not add any comment or text, such as “Interfaces are “. A hypothetical example of an answer in the correct format is 2, 3, 4. Spaces do not matter. 16. (1 pt) After event 1 has happened, what is/are the non-blank entry/entries of the switch table? List the content of each non-blank entry as a tuple . Write only the MAC address, and the interface number, separated by a comma. If there is more than one non-blank entry, list the tuples by order of increasing MAC address. As a hypothetical example, if there are two non-blank entries: MAC address: C, mapped to interface 1 MAC address: A, mapped to interface 3 Your answer should be