Get (Retrieve) W3SVC path in ASP.Net

I use below code to get App Pool details, but it throw error not able to find path.

string appPoolPath = @"IIS://" + System.Environment.MachineName + "/W3SVC/AppPools/" + appPoolName;
DirectoryEntry w3svc = new DirectoryEntry(appPoolPath);

I have two questions :

1. What is the actual path it is looking for.

2. How to resolve this issue.