Question

What is the easiest way to query the Active directory to get a strings list of departments names. Example: “Finance”, “Marketing”, “IT”,etc.
My case is an active directory for an enterprise with well over 3000 users.

Answer 1

Assuming that you just want to get a list of objects with the Department attribute returned you could use a DirectorySearcher in the System.DirectoryServices namespace.

Then your filter would be something like:

ds.Filter = "(objectClass=user)";

and you could then tell the searcher to just load the department attribute:

ds.PropertiesToLoad.Add("department");

Then enumerate throught the result set:

SearchResultCollection results = ds.FindAll();

Then add each department property to a Dictionary to get all the unique values

 foreach (SearchResult result in results)
 {
   string dept = String.Empty;
   DirectoryEntry de = result.GetDirectoryEntry();
   if (de.Properties.Contains("department"))
   {
     dept = de.Properties["department"][0].ToString();
     if (!dict.ContainsKey(dept))
     {
       dict.Add(result.Properties["department"][0].ToString();
     }
  }
}

Alternatively, there are command-line tools which will give you this information such as dsquery or adfind.

adfind -default -f "(objectclass=user)" department -list | sort

will give you a sorted list of the department attributes for all users.