how many listeners should be?

  i found some issues. There are 2 listeners running. Listener and mine new one 'test'. Listener uses port 1521 and test uses 1564. i did 1.set current_listener test

Listenet is test set.

2. lsnrtcl stop

3. snrctl start test

it works now, and i can connect to my db_server with port numbr 1564.

And now i'm confused, where has come from listener with alias 'listener'? i choose custom installation and it musnt install default listener, right? if i'm mistaken i have to have just listener which have the name test.

i read a lot of articles about Oracle's network configuration. and there arent any best one. For examples there always the same and default config for listener. there isnt whole info about, what to do if i want to change port number. is it enough if i change service name and port number or ...