Editing BitTorrent (section)

=== Multitrackers ===
Another unofficial feature is an extension to the BitTorrent metadata format proposed by John Hoffman<ref>{{cite web|url=https://www.bittorrent.org/beps/bep_0012.html|title=BEP12: Multitracker Metadata Extension|publisher=BitTorrent Inc.|url-status=live|archive-url=https://web.archive.org/web/20121227233108/http://bittorrent.org/beps/bep_0012.html|archive-date=27 December 2012|access-date=28 March 2013}}</ref> and implemented by several indexing websites. It allows the use of multiple trackers per file, so if one tracker fails, others can continue to support file transfer. It is implemented in several clients, such as [[BitComet]], BitTornado, BitTorrent, [[KTorrent]], [[Transmission (BitTorrent client)|Transmission]], [[Deluge (software)|Deluge]], [[μTorrent]], [[rtorrent]], [[Vuze]], and [[Frostwire]]. Trackers are placed in groups, or tiers, with a tracker randomly chosen from the top tier and tried, moving to the next tier if all the trackers in the top tier fail.

Torrents with multiple trackers can decrease the time it takes to download a file, but also have a few consequences:
* Poorly implemented<ref>{{cite web| url=http://wiki.depthstrike.com/index.php/P2P:Protocol:Specifications:Multitracker#Bad_Implementations| title=P2P:Protocol:Specifications:Multitracker| access-date=13 November 2009| publisher=wiki.depthstrike.com| archive-url=https://web.archive.org/web/20140326095037/http://wiki.depthstrike.com/index.php/P2P%3AProtocol%3ASpecifications%3AMultitracker#Bad_Implementations| archive-date=26 March 2014| url-status=live| df=dmy-all}}{{dubious|reason=Wikis are not citable sources – find a better source-Lexein|date=April 2013}}</ref> clients may contact multiple trackers, leading to more overhead-traffic.
* Torrents from closed trackers suddenly become downloadable by non-members, as they can connect to a seed via an open tracker.