I am looking for the best options on connecting my SharePoint list with external data sources like SQL database and exchange servers to update the contacts list automatically. I am using SharePoint 2010. Any suggestions on this.
For SQL databse you have to use BCS, Can you please what do you mean by contact list ? It is custom list ? If so again you have to use BCS...
http://blog.arjanfraaij.com/2011/07/sharepoint-2010-using-bcs-with-sql.html http://www.codeproject.com/Articles/60190/Business-Connectivity-Services-in-SharePoint https://msdn.microsoft.com/en-us/library/office/ee557243(v=office.14).aspx
Hope this help!!!