Scale-free networks tolerate random failures well but fragment under targeted removal of their hubs.
Albert, Jeong and Barabási's 2000 result, called robust yet fragile. The internet survives random router failures and would fragment under attack on the largest few, which is why hub protection is a distinct security problem.
In practice
- A payments network survives thousands of merchant outages and stops entirely when one clearing house fails.
- A supply chain absorbs a dozen small supplier failures and halts when the single certifying laboratory closes.