In general, are attack spells affected by armor like a normal attack, or are attack spells' attacks treated as direct damage?

Example: Warlock casts a Fireball on a Steelclaw Grizzly (which has 3 Armor and 15 Life).  Six dice are rolled equaling 0, 0, 0, 1, 1, 2 critical.  Is all damage treated as direct damage, thus causing 4 total damage, or is the total damage equal to 2 for just the two critical damage (the 1 and 1 dice rolls are absorbed by the armor)?

Thanks in advance!