0) Make sure your logon name is shorter than or equal to 20 characters, this could save you from having some issues
1) Grant the AD user the correct rights in the database, via SQL Management Studio
2) Modify the connection string as follows :
<add name=”MyConnection” providerName=”System.Data.SqlClient” connectionString=”Data Source=MyDatasource;Initial Catalog=MyDB;User ID=login;Password=password” />

becomes

<add name=”MyConnection” providerName=”System.Data.SqlClient” connectionString=”Data Source=MyDatasource;Initial Catalog=MyDB;Integrated Security=SSPI” />

3) Add the following in the web.config :

<identity impersonate=”true” userName=”MyADDomain\Login” password=”password”/>

4) Add the MyADDomain\Login in the IIS_USRS.
Launch the Computer Management; Go to System Tools -> Local Users and Groups -> Groups, notice the IIS_USRS group, and add your active directory into it.