Oracle Database Discussions

Hello all,

I am very nice to administrations side of oracle. Actually just trying to move towards DBA side. Right now, i am a pl/sql developer. But with help of other DBA, I do know a little bit of stuff about the database. some v$view etc etc...but in one of my interview for a jr. DBA. I was asked what I would do or what steps I would do resolve a problem like below...
lets say the DB performace is going up and down....so lets say at 2:00pm, the DB is good and then at 2:02pm the performace is bad and then at 2:03 the perf is good ...so on....and my response was look at the v$session_wait or v$system waits...find out how many users are there at one given point....as v$veiws are dynamice....i would look at the DBA_hist table in AWR to find the trend.....but seems like he was not very happy with my answers....as he said...thats it....and I said....I could not really think of anything else besides that....

so I wanted to ask you guys, what you guys would do in such a case, where one min the perf is good and one min the perf is bad ???

also question2. that i wanted to know about was...what would you do when all the transations are hung .... and my answer was...i would first try to see if i could login to sql and query the v$views and see if i find anything there or look at the v$lock to see if we have any blocking session.....and his response was...what if there are no locks and you cant login....i went blank...but did said...would run some hang analysis trace....

so what would I do in this situation ???