Defensive Index Question (Little Upsilon)

Out of curiosity...
Do my weapons have to be activated to contribute to the defensive index? Will they contribute less to the defensive index if I deactivate them?

They must be activated. Ammo does not contribute to the Index tho.

what is the best way to improve my defensive index ?
as in what to buy ?

Missile Interceptors are the most cost effective according to the documentation.

MIB's, radar planes, a few other things make it rise very fast which is all well and good for leveling purposes, but if you want to do it correctly I recommend buying Interceptors/ Defensive Heli's with ammo DMB AAMB MIB all equally in amounts with ammo, etc..etc..but if you are just trying to level up and not war on WG then MIB's should do okay for your purpose, just don't get the wrong idea about them, they wont defend you against everything..

I use 2001 MIB garrisons myself, works a treat ;)