Slices are not given out by the clients. Let me try to illustrate. Imagine that your slices are storage containers in a storage facility. Each slice has a number. You come in and you want to use a container. Which one? We then take you name, SSN, eye color, DOB etc. and hash. As a result we get a number. This number is the number of your storage container. Same here. The part of the SID is the unique identifier that identities the domain. The hash of it will always have number X. This number will always define which storage container (slice) would be used for your domain. There is a chance that some other domain would have the same number but the probability is very low. No you can configure how big slices are. The bigger the slice the smaller the number of the slices. So X might map to a different container if you start re-configuring things and reducing the width of the slices. HTH.