Basic questions about tnsnames.ora

Question

I think I am quite confused about tnsnames.ora file (this is about release 9.2).
- I was told that a tnsnames.ora file is only necessary in the server side when you need to connect to a different remote database, but if I do not have any entry in my server tnsnames.ora then, how can the listener know which services it has to listen to?
- I do not understand what "Dynamic service registration" is and how it can be used.
Sorry if the level of these questions is too low for this forum, but I have not found clear answers for them.

Answer 1

- The listener knows which services it has to listen
for by
static registration --> the database definition is in
listener.ora
dynamic registration --> the PMON process of the
database registers itself with the listener,
submitting the service_name parameter from the spfile
| init.ora
Tnsnames.ora is a client thingy, when connecting to
a remote database, the local database is a client
for the remote database.
Hth
Sybrand Bakker
Senior Oracle DBAThank you for the answer.
I made a wrong conclusion, my situation is this (there are 2 database instances in one server and the listener.ora has no list of services, so I must assume both instances are registered dynamically, am I wrong?):
I wrongly thought that the tnsnames.ora played some role in the server side because after restarting the listener I commented the entries in the server tnsnames.ora and the listener had no service registered, then I uncommented those entries and I saw that then the listener had those services registered. I guess that what it actually happened is that it takes a little time for the listener to register dynamically after it is restarted, can it be the case?
I have read both init.ora files but I cannot see what parameter is set to register dynamically, maybe it is only defined at spfile level. Can someone tell me what parameters must I look for?
One more question. I have been asked if a database must be restarted to work ok when the server ip is changed (I suppose it is done without shutting the server down). Does someone know? Should the listener also be rebooted?
Thanks again.