Examine this command executed on a client that is remote from the database server.
SQL> CONNECT hr/hr@orcl
Which two are required for this command to connect the SQLPLUS client to a database instance?
A) A service name must be defined to the listener that matches the service name in the orcl TNS entry.
B) An orcl TNS entry must be defined in the client-side tnsnames.ora file.
C) An orcl TNS entry must be defined in the client-side and server-side tnsnames.ora files.
D) The service name orcl must be defined to the listener.
E) An orcl TNS entry must be defined in the server-side tnsnames.ora file.
Answer：AB
(解析：远程连接，客户端需要配置tns，服务端要配置监听，而且对应的service要匹配。来自3组：1015267481)
原文：https://blog.51cto.com/13854012/2386006