MS SQL web application development

i am developing web based registration system.
using MS sql and C#,asp.net.
the system will be deployed both on local computer and on the internet.
when there is internet connection, the user will access the site using internet and register users on that. but so many reason
the system should also work offline, user could be registered on offline system then when the computer is connected to internet.
the database parts should be syncronized(copy automatically to the live server on the internet).
is that possible to do that?
how to begin please.

Well, if the user might not be connected to the internet then you obviously can't use a web site. If the user's offline then they can't see any web sites because they can't see the web. You'll need to create a Windows application that connects to a web service. You should look into using the Microsoft Sync Framework, which is designed specifically for occasionally-connected applications like you describe. I've never used it so I don't know all the details but basically you have a local database that is used if there is no internet connection, otherwise the data goes off to an internet store.

http://msdn.microsoft.com/en-us/sync/bb736753.aspx

If the user is registering offline, how are you guaranteeing that there are no conflicts between registered users?

If you want the user to be able to use it *after* registering, using a Sync Framework like jmc has suggested will work, but if you want the user to register while offline, I'm not sure that will work.

One way around the registering part is not to require the user to register at all if they're offline, but as soon as they get online, it requires them to create an account otherwise the data will not sync. Of course, this is all assuming that the user isn't accessing anything that any average Joe could access without registering to the system.