It is quite frustrating that none of the questions involving "vacances" accept "holidays" as part of the answer. In Australia one would usually say "Where do you go on your holidays?" with a plural "holidays" rather than singular... It feels quite unnatural to use the singular.
My answer, "Where are you going on your vacations?" was accepted, but I have to wonder about that; my answer asks about an event that hasn't happened yet but will at an unspecified point in the future. Duo's suggested translation, "Where do you go for your vacation?" asks about an ongoing practice, something that has taken place at some point and is likely to happen again in the future.
My question: is the meaning of "Où allez-vous pour vos vacances ?" really that ambiguous, or is Duo simply being overly liberal by accepting my translation?
In French, holidays, vacation, is always used in plural form. There are quite a few French nouns that can only be plural, sometimes because the noun has a different meaning in the singular. You can view the full list here: http://french.about.com/od/grammar/a/singularplural_4.htm
Just a word, note that "vous" is the plural form of "you" but it is translated simply as "you". Some people do say "you all" which can take a range of meanings: informal colloquialism referring to several people or as a stressed plural form when addressing a group and you want to emphasize that you are speaking to all of them. In English, "you" can be either singular or plural, just like "vous" can be either singular or plural. However, if you really want to say "you all", then you would say "vous tous". And unless the French says "vous tous", then "vous" is simply "you".
In regard to "vacances", it is plural in French, but translates in English to the singular (vacation, holiday, although some regions say holidays).
The literal translation would be "Where go you for your holidays?" It's "your" holidays. Not "the" holidays.
In Australia, if I asked "where are you going for YOUR holidays?" it may mean that I'm not having a holiday at that time. You might have taken a week off work.
If I asked "where are you going for THE holidays?" it probably means I am referring to a holiday which everyone else is having at the same time, like school holidays, for example.