Here you go,
this link should help to clear everything up. Since joining the IRON Council and being appointed the DMoD I've had to keep abreast of these changes. Also there is discussion of changing the DefCon system so you can only shift up or down by one level per day. So many people spoke out against it Admin has suspended the change for now. So say for example you are in DefCon 5 and someone attacks you. If this change passes it will take you four days to get to DefCon1.
DefCon5 = Day 1 You are attacked
DefCon4 = Day 1 In response to the attack that day
DefCon3 = Day 2 Still getting pounded
DefCon2 = Day 3 Still getting pounded but most tech raids start to wrap up when target is active
DefCon1 = Day 4 Most tech raids on actives are over by now