Editing Scalability (section)

==Domains==
* A [[routing protocol]] is considered scalable with respect to network size, if the size of the necessary [[routing table]] on each node grows as [[Big O notation|O]](log ''N''), where ''N'' is the number of nodes in the network. Some early [[peer-to-peer]] (P2P) implementations of [[Gnutella]] had scaling issues. Each node query [[Query flooding|flooded]] its requests to all nodes. The demand on each peer increased in proportion to the total number of peers, quickly overrunning their capacity. Other P2P systems like [[BitTorrent (protocol)|BitTorrent]] scale well because the demand on each peer is independent of the number of peers. Nothing is centralized, so the system can expand indefinitely without any resources other than the peers themselves.
* A scalable [[online transaction processing]] system or [[database management system]] is one that can be upgraded to process more transactions by adding new processors, devices and storage, and which can be upgraded easily and transparently without shutting it down.
* The distributed nature of the [[Domain Name System]] (DNS) allows it to work efficiently, serving billions of [[server (computing)|hosts]] on the worldwide [[Internet]].