string LdapPath = @"LDAP://" + DomainServer.HostName + "." + domainName + "/" + strOuCn;
DirectoryEntry adEntry = new DirectoryEntry();
adEntry.AuthenticationType = AuthenticationTypes.ServerBind;
adEntry.Path = LdapPath; //loads OU to adEntry
тогда вы можете проверить свои свойства, например:
adEntry.Properties["distinguishedName"]