Synchronize user details between Active directory and CRM

Hello All,

I need your help on the following, I have a requirement from client who is using CRM 2011 on primes, to provide him a continues integration and synchronization between user details in AD and in CRM. So he needs to make changes in active directory user details and these changes will be reflected automatically in user record in CRM. So is that possible to be done and if yes how and what is the best approach?

Thanks