Although it decommissioned nearly 10,000 servers, AOL bought new hardware to replace most of them, so on balance it reduced its server count by only about 1,000. But the new gear is virtualized and more energy-efficient, which reduced AOL's utility bills, Rian said.

Its net savings came to about $4 million, including $2.2 million in software licenses from migrating away from its Sybase database applications, she said.

AOL beat five other competitors; the closest runner-up, NBCUniversal, removed 284 servers. AOL put together a to celebrate its win.

The Uptime Institute manages the data-center tiering system. Its for data-center managers takes place in May in Santa Clara, California.