Anil.... Sorry I didn't jump on yesterday to answer you....
if you wish to live in Fairfax county, there is information available on their web site....see this link. http://boundary.fcps.edu/boundary
This allows you to see the maps, but also allows you to type in an address and see what school district it falls in. And, you are getting your information straight from the source.
Some earlier posters made valid points that an agent can search the MLS by school district. If you'd like (I know you are not moving for awhile), I can set you up with an automated search if the MLS specifies the schools. But, it is a "garbage in/garbage out" gamble... it's up to the listing agent to include the information in the listing. If they list the wrong school or no school, then it won't be caught by such automated search criteria. At this point, you are starting to look early enough that it still might be helpful - you can kind of watch what home values are doing in those areas and get an idea of the homes available in those areas. Just email me firstname.lastname@example.org if you'd like this - no catch or obligation, and you can disable the search at any time if you choose.
Also, please bear in mind that school boundaries do change, in some areas more frequently than others, depending on new development/expected enrollment and funding. Stuff a REALTOR can't know with certainty any earlier than the general public. That is why some agent choose not to put the information in the listing.
Hope this is helpful. Have a great evening!