Since the release 10g of Oracle RDBMS onward, dbca has been included in the installation binaries as a native tool for DBAs to create and maintain database (RAC or not), service, asm and other database features.
Evolved smoothly over the time, it is today considered by many professionals a stunningly user-friendly, much enriched in features, and extremely powerful tool that a DBA can expect. Some tasks that used to be demanding and time-consuming in the past can now be completed in a brief time period with several mouse clicks and a few typing.
I was really impressed by dbca today myself. Having been working on quite a few tasks for diverse applications, I was asked to squeeze in one more task to provide some other users tips for their connection error troubleshooting. A quick glance at the databases instances running on that server, I found with disappointment that the 2 databases they were trying to connect to did not even exist! Now I either to tell them to get lost (sorry for the rough words) or to create the two databases in a very short notice and then provide them permissions and connect data. Sadly, the former was not really a choice — I had to go after the latter.
And that was the time I bet my hope on dbca. And it did not let me down! In only about 20 minutes, I got 2 RAC databases created together with services set for them! How good is that? The wide-open eyes of my team lead tell it all!
DBCA, way to go!