Quite often, travel is a necessary part of this job, but not always. Answer this question honestly but with tact. If you're not willing to travel for work, don't say that you are. Phrase your answer in a way that shows you're a team player. If you're willing to travel for work or have in the past, volunteer. If you're not open to traveling, don't say no. If you weren't aware travel was a prerequisite for the position, ask if it is. Tell them you're interested in the position and that you'd be open to discussing it further, but your understanding of constant business travel doesn't fit into your current lifestyle. Ask more questions about the position, be flexible, and be open to negotiation. There may be room for advancement from within, for which a willingness to travel may be a prerequisite.