Since I doubt heavily that they are paying you for experience you don't have....learn as fast as you can, learn to be good using the tips above, and THEN look to have your position adjusted.

Sounds to me that someone is trying to get a DBA "on the cheap". A good DBA tends to have a lot of challenges and responsibilities to take on. Once you understand what your real responsibilities are, and how to do them well, and you've proved yourself - don't let yourself be taken advantage of.

In other words - be careful that a short term "opportunity" doesn't turn into a long-term S***ing opportunity of you by the organization....