Which statement is true about Oracle Net Listener?
A.
It acts as the listening endpoint for the Oracle database instance for all local and non-local user
connections.
B.
A single listener can service only one database instance and multiple remote client
connections.
C.
Service registration with the listener is performed by the process monitor (PMON) process of
each database instance.
D.
The listener.ora configuration file must be configured with one or more listening protocol
addresses to allow remote users to connect to a database instance.
E.
The listener.ora configuration file must be located in the ORACLE_HOME/network/admin
directly.
Explanation:
Supported services, that is, the services to which the listener forwards client
requests, can be configured in the listener.ora file or this information can be dynamically registered
with the listener. This dynamic registration feature is called service registration. The registration is
performed by the PMON process—an instance background process—of each database instance
that has the necessary configuration in the database initialization parameter file. Dynamic service
registration does not require any configuration in the listener.ora file.
Incorrect:
Not B: Service registration reduces the need for the SID_LIST_listener_name parameter setting,
which specifies information about the databases served by the listener, in the listener.ora file.
Note:
* Oracle Net Listener is a separate process that runs on the database server computer. It receives
incoming client connection requests and manages the traffic of these requests to the database
server.
* A remote listener is a listener residing on one computer that redirects connections to a database
instance on another computer. Remote listeners are typically used in an Oracle Real Application
Clusters (Oracle RAC) environment. You can configure registration to remote listeners, such as in
the case of Oracle RAC, for dedicated server or shared server environments.
Answer C is not correct as PMON used to Listener Registration Prior Rel 12c. From 12c LREG process does Listener Registration
ADE
As stated by winner2001 – in 12c LREG is reponsible for dynamic registration.
Therefore D because:
As a minimum the listener.ora file must include a section for one listener that states its name, the protocol and the listening address it will use.
Answer : A
Ref : From 12c onwards service registration with listener is being done by LGRE background process not PMON
https://docs.oracle.com/database/121/REFRN/GUID-86184690-5531-405F-AA05-BB935F57B76D.htm#REFRN104
Option D is correct but not very appropriate, as per below url
https://docs.oracle.com/database/121/NETAG/listenercfg.htm#NETAG292
Overview of Oracle Net Listener
A listener is configured with one or more listening protocol addresses, information about supported services, and parameters that control its runtime behavior. The listener configuration is stored in a configuration file named listener.ora.
Because the configuration parameters have default values, it is possible to start and use a listener with no configuration.
So as per above statement from Oracle doc its not mandatory to configure listener with a protocol. It would pick default configuration