Well, I can't go around telling Everyone - not publically.

However,

My first is in mile, but not in yard
My second is in air, but not in dirt
My third is in pizza, but not in pasta
My fourth is in bonanza, but not in dallas
My fifth is in monkey, but not in ape
My sixth is in banana, but not in apple.

And if you can work that out, you get a medal, muttley.