I have walled off part of sanctuary, leaving two entrances at each end for the main road, and posted defense in front of each. My defense rating is 30 something. It's composed of the following: two turrets, and a spotlight on each entry, and a defense position for assigned settlers near each entrance as well.

I haven't been attacked yet that I know of. Is that normal?

a. I only have eight settlers thus far. Is that too small a number to draw an attack?

b. what is a high defense rating? If it is sufficiently high do you not get attacked at all?

Hope these questions aren't too dumb. I've got about 17 hours in and I've not even scratched the surface of this game, so I'm still pretty ignorant regarding its mechanics.

I'm at a similar place and am wondering the same thing. Also, I only have about a quarter of Sanctuary walled off, with the idea that its easier to defend a smaller space, but whenever I stop by I find my settlers wandering all over the place. How do I get them to stay safely inside the walls?

I think the settlers will continue to wander all over the 'ringed' area of the settlement whenever they're not carrying out assignments. Most of my settlers stand in weird places when not working on the crops. I have a two-story "dorm" with lots of chairs, couches, and beds and I don't think anyone sleeps or sits in any of them. Once in a while I'll find someone standing creepily in a dark corner Blair Witch style but that's about it. There are lots of things to learn with the settlement building, and I think it's going to be the target of some patches hopefully. Also, at the risk of drawing hatred, just think of the mods that are going to come out for this! Man, in a few months you'll be able to build cities. I'm sure there will be ways to increase the radius of your town and flag more objects as scrap-able. That will certainly tax PC's but I'm sure it's doable.

Still, I wonder about the lack of attacks.

I completely shut off my Sanctuary Hills base from the outside world, having around 60 defense now and only ~30 food+water, so my base it not near getting the low defense warning, which I assume might be the only way to get attacked?

One of my 2 people settlements was attacked recently because I didn't care about building defense there and it happened when I had the "!" warning sign next to defense. So maybe you cant even get attacked while having proper defense?

You only get attacked if your defense is lower than your food or water. It's more of a deterrent than a defense.

You can. I've had Abernathy Farms attacked with my defense 10 higher than minimum needed. From wht i understand, lower than min defense of food+water rating invites more attacks. Defense higher than min reduces attacks but does not make it zero.