Dagongmen, Nanxinxun, Dingling and Changling Station

Where exactly the location of Dagongmen Station? Is it the same with Dingling Station? I knew that we can go from Badaling to Sacred Way, Dingling and Changling with bus 879, but which station that we should get off to reach each of them? And, which station that you prefer for us to take bus 872 to go back to Deshengmen Bus Station? Oh! and how about the distance from Sacred Way to Dingling? is it walkable? Thank you!!!