As Blizzard continues to update its infrastructure and the classic games move into a maintenance phase, understanding the index server helps us appreciate how far online gaming has come. From the raw packet handling of BNCS to the cloud-scaled architecture of today, the index server was the unsung hero that turned isolated single-player campaigns into a global community. For those maintaining private PvPGN servers or digging through the bnetd.conf file today, preserving the functionality of the index server is key to keeping the golden age of Starcraft and Diablo II alive.
5. The Evolution to Battle.net 2.0 and Modern Cloud Infrastructure
To understand why an "Index Server" was so vital, one must look at the data it was indexing and serving. Classic Battle.net operated on a proprietary protocol that pre-dated many of today's API-driven services.