Some parents enroll their children in daycare for socialization so I can understand why some would ask. They also probably ask because it's just human nature to want to know what is going on, especially when your child is involved. They are likely curious and want to know if their child will be having a new friend to play with. Some will be asking just because they are nosey!! Even when I worked in centres, we had parents ask where so and so was.

If you don't like explaining it, just say something like " So and so has moved on and I am now looking at filling their space. If you know someone needing care please send them my way"

I started doing a monthly newsletter last Fall and when children leave or start at daycare, I mention it briefly in the newsletter. This way I'm not explaining to the all the parents (only the ones that ask further questions) and they know what is going on at the dc their child attends. I have a small group and the parents all talk and their children are quite close so when one leaves, it's no secret anyways.