Your tnsnames.ora file has the following entry for the service alias ORCL：  ORCL = 
（DESCRIPTION = 
（ADDRESS = （PROTOCOL = TCP） （HOST = 10.156.24.216） （PORT = 1521））  
（CONNECT_DATA = 
（SERVER = DEDICATED）
（SERVICE_NAME = orcl.oracle.com）
  ）  
）  
The TNSPING command executes successfully when tested with ORCL but you are not able to connect to the database instance with the following command：
 SQL> CONNECT scott/tiger@orcl 
What could be the reason for this？（）

Examine the following commands executed in your database： SQL> ALTER SESSION RECYCLEBIN=ON； Session altered 
SQL > CREATE TABLE emp TABLESPACE tbsfd AS SELECT * FROM hr.employees； 
Table created. 
Further， you executed the following command to drop the table： 
SQL> DROP TABLE emp；Table dropped. 
What happens in this scenario？（）