I can't see where they differ too much.
So the firewall exam is changing at the end of the month from 642-617 to 642-618. I checked the exam topics on the cisco website and cant really differentiate much between the two.
If I have been studying with materials for 617 can I sit for the 618 without having to read a new book designed just for the 618 exam? I would hate to have to purchase a new book even though I am basically 99% ready to test.

Thanks for your time.