Why a 2,000-pound bomb defeats practical carrier armor

What armor would an aircraft carrier need to defeat a 2,000-pound armor-piercing bomb?

About six inches at the flight deck plus another heavy deck below, a protection scheme too weight-intensive for a practical contemporary carrier.

Defeating the weapon would require roughly six inches of armor, likely backed by another substantial armored deck below. That layered scheme might catch a bomb after it penetrated the flight deck. Its weight would exceed practical carrier protection and impose major costs on air-group capacity, stability, and the rest of the design.