The worst thing you can do during an interview is guess the answer. This indicates you do not have the knowledge needed to answer the question and that you're willing to take a chance on being wrong. It is much better for you to ask a qualifying or clarifying question or explain to the interviewer that you are not familiar with the technology and then describe how you would find the answer for them. Interviewers will always appreciate honesty during the interview, even if you don't know the answer to their question.

"A CAN transceiver provides differential transmission and receive abilities to the bus and CAN controller. It provides an interface between the protocol controller and the physical bus in CAN node. Each node in a CAN system must convert the digital signals generated by a CAN controller to signals suitable for transmission over the bus. The CAN transceiver provides a buffer between the CAN controller and the spikes that may occur on the CAN bus by outside sources such as EMI, ESD, and other transients."