Just recently I came across another unclear error message while troubleshooting an Oracle Instance registration with SCAN Listener. This post is one of the posts which may save quite a bit of time for people who will hit the same issue.
The errors message I got configuring a database just moved to run under 11GR2 Oracle Cluster control is as following:
SQL> alter system set remote_listener='scan.usolygrid-prod.cinram.com:1521'; alter system set remote_listener='scan.your.domain.com:1521' * ERROR at line 1: ORA-02097: parameter cannot be modified because specified value is invalid ORA-00119: invalid specification for system parameter REMOTE_LISTENER ORA-00132: syntax error or unresolved network name 'scan.your.domain.com:1521' SQL>
I was quite sure that the syntax I used was 100% correct as other instances running on the same host used the same remote_listener parameter value.
It appears that someone adjusted the following string in sqlnet.ora file on the server:
from NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT) to NAMES.DIRECTORY_PATH= (TNSNAMES)
The change makes sense to me as it always good to have strict control on where tns names are sourced from on the servers side.
However it appears that Oracle use an easy connect naming method to register Oracle Instances in SCAN Listeners by default. Therefore EZCONNECT keyword should be present in sqlnet.ora file. Strictly speaking you can use other tns names as the resolution method for the remote_listener parameter but by default it uses the easy connect naming method and you may face the error message shown above if you omit the EZCONNECT keyword.
I hope this post may save you some troubleshooting time.