Ward Question

When are wards broken?

For example, If I cast a standard ward against the infernal around myself, the ward is broken when I cross the circle (the semi-circular dome around myself), correct?

However, if a ward against the infernal is cast around the infernal creature to hold it inside, what designates breaking the circle? Does anything that crosses the "dome" of the ward break it (with the exception of the infernal creature)? Or just if the circle itself is harmed? Or is it when the caster crosses that circle?

The rules state:
RING DURATION: Â The spell lasts until the target of the spell moves outside the ring. Â (the target is the thing protected.)

But the Target of a standard ward is the Circle, (rather than the mage). So I'm damn confused.

Wards are a broken segment of the rules. Well, not "broken", but problematic. In the example you cite, I would say that the ward is broken when the caster crosses the circle or it is broken by something else. The demon cannot cross.