Change DBNAME or DBID using nid Oracle 10g/11g

nid  ---- (NEW ID)

DBNEWID: Release 11.2.0.2.0 - Production on Sun Mar 20 22:17:55 2011
Keyword Description (Default)
----------------------------------------------------
TARGET Username/Password (NONE)
DBNAME New database name (NONE)
LOGFILE Output Log (NONE)
REVERT Revert failed change NO
SETNAME Set a new database name only NO
APPEND Append to output log NO
HELP Displays these messages NO

To Change Database ID/NAME :
1) Database must be mounted exclusively, if run command in other status you will get the following error

NID-00120: Database should be mounted exclusively

If you running RAC , you need to stop all the nodes and set CLUSTER_DATABASE=FALSE ,before restarting the database instance in mount state.

2) nid TARGET=sys/password@TNSENTRY