Google behavioral based interview questions.

I used to work in HR/recruiting, and these kinds of questions are the type that research shows are most effective.

What is your discipline style, how comfortable are you prepping food, what kind of food do you prep, what do you do when baby is napping, what do you do to fill your day with a 9 month old, give examples of injuries you tell parents about and those you don't, what do you do when you get frustrated with the baby, are you comfortable getting in the pool with the baby, do you travel with families, etc.

What kinds of things do you do with a 9 mo old? What about a 12 mo old? What do you do if the baby cries and won't stop? How much experience do you have with infants, how old was the baby and how long did you work for the family? Are you comfortable taking the baby on outings to xyz locations? Do you have a car seat and do you know how to install it properly? What are your long term career plans? Are you in school? What kinds of things should a baby this age be eating/doing? (shows if she's up in developmental milestones.)

How do you do your work?

As a lifelong professional in this field, I could easily speak to that question for as you as you would like to listen.

What questions do most people ask when interviewing a nanny for an infant (our DS is 9mo old). Outside of the basics of "do you have a clean criminal and driving record". What else should we be asking about in regards to them as a person and as a care taker.