Active Directory replication en VPN

[Guest]

Hi,

i have a qestion about Active directory,

i have an registered domain with publiek ip adress (example.com) en now i
want to create en sub domain say : something.example.com this sub doamin
going to have en privet ip adress en he is going to be behind en router.
now i would like to know how this to AD in 2 diffrent site going to replicte
to each other?

i know that i have to create en site for each one of them en make a site
linke for both of them. do i have to create some kind of vpn between this to
PC?
if yes could some one send me some info about how to use vpn for AD
replication?

thankx.