2003 impala front bearing hub assembly

I was just wandering on the bearing hub assembly on a 2003 impala front. on the part of the bearing that goes in first it has 3 spaces all around it 2 little ones and a bigger one. Does the bigger one have to go down? Thats the way the one i took off was and i put it on that way. Just want to know why it would be like that because the knuckle has no groove where that would go into.

thanks
garys

Front or rear?

Front or rear?
front