How to get nested groups (subgroups) in system.directoryservices.protocol in C#

See more:

C#3.5

LDAP

active-directory

I have a function which gets parameter as Distringuished name of a group and returns the nested groups or groups within a given group using SearchRequest query and SearchResponse. The code works fine when i use DirectoryEntry but failse when i use LdapConnection class. It is necessary to work with LdapConnection class. Please find below the code snippet :-

public static void GetNestedGroups(string strGroupDN)
{
    var _currentDomainofLoggedinUser = Domain.GetComputerDomain();

    var currentDomainofLoggedinUser = Domain.GetComputerDomain();
    var currentDomainController = currentDomainofLoggedinUser.FindDomainController(); //Gets the current Domain controller

    var domainName = System.Net.NetworkInformation.IPGlobalProperties.GetIPGlobalProperties().DomainName;
    string strPath = "LDAP://" + currentDomainController.Name; //Gets the current domain controller name
    AppDomain.CurrentDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal);
    using (LdapConnection ldap = new LdapConnection(new LdapDirectoryIdentifier(domainName, 636)))
    {
        ldap.AuthType = AuthType.Basic;
        ldap.SessionOptions.SecureSocketLayer = false;
        var s = new SecureString();
        NetworkCredential network = new NetworkCredential(WindowsIdentity.GetCurrent().Name, s);

        string ldapSearchFilter = String.Format
              ("(&(memberOf={0})(objectClass=group))", strGroupDN);
        NetworkCredential cred = CredentialCache.DefaultNetworkCredentials;
        ldap.Bind(network);
        string[] attributesToReturn = new string[] { "distinguishedName" };


        SearchRequest searchRequest = new SearchRequest(strGroupDN, ldapSearchFilter, SearchScope.OneLevel, attributesToReturn);
        searchRequest.DistinguishedName =
            strGroupDN;


        searchRequest.Filter = String.Format
               ("(&(memberOf={0})(objectClass=group))", strGroupDN);
        SearchResponse response = (SearchResponse)ldap.SendRequest(searchRequest);
        if (response != null && response.Entries.Count > 0)
        {
            SearchResultEntry obj = response.Entries[0];

            var groupCount = ((System.Collections.CollectionBase)(obj.Attributes["memberOf"])).Count;
            foreach (SearchResultEntry entry in response.Entries)
            {
                var groupName = entry.DistinguishedName;
                _subGroupList.Add(groupName.ToString().Split('=')[1].Split(',')[0]);
                GetNestedGroups(groupName);
            }

        }
    }
}

In the response it doesn't give anything. (In case of DirectoryEntry, it does provide the result)

What I have tried:

As i am new to LDAP and active directory , i have referred :-

Introduction to System.DirectoryServices.Protocols (S.DS.P)[^]