E.S.
I would be understanding. My two year old has bitten and been bitten.
See, the thing is, children of this age can't (or can't properly) communicate with words. So if they feel threatened they will use actions - biting, hitting, etc. It's the way humans work. Once my daughter could communicate better, the biting stopped.
Now, I wouldn't expect the daycare to do nothing. They should absolutely respond and let the biter know it's not okay. I think each child and situation is different and should be addressed based on that. Some say to give the child who was bitten comfort first to let the biter know the action did not bring attention. But the child might not have been biting for attention. Definitely let the biter know to communicate with words and not aggression.
Also, the daycare MUST be consistent in it's reaction to biting. I witnessed my daughter get bitten and they did NOTHING to the child who bit her. Once my daughter was comforted, she went back to her classmates and the biter proceeded to hit my daughter repeatedly on the head. And my daughter hadn't done anything to this child. But one time when I walked in after my daughter had bitten another child they were treating my daughter like she was the devil, giving her evil looks and all (the teachers were!). I believe discipline must be fair and consistent so the child can understand the consequences of their actions.