A netsplit is a malfunction seen in Internet relay chat (IRC). When a user experiences a netsplit, a series of messages will display within each chat room that makes it look like a number of other IRC users have logged off. This occurs when a server or mode gets disconnected from other servers within the same IRC server network. Generally, this occurrence rights itself on its own within a few minutes of the split. A server split on IRC can open users up to a few minor user attacks that are more annoying than destructive.
IRC is a chat client that gives a user access to a series of networks that house multiple user-administrated chat rooms. Functions within IRC differ depending on the server and can sometimes include password protection of the user's nicknames, called nicks on the server, and password-protected control over chat rooms that a registered user has claimed. When a server does not have password protection of nicknames, any new user can log onto the server and take any nickname that does not belong to someone who is currently logged on to the server. During a netsplit, some users take advantage of these servers by taking the nick of another user who has been disconnected by the netsplit. Depending on the server, this may mean that the original user cannot adopt the nick again until the usurper leaves.
On servers with password protection for user nicks, the system automatically changes the nick of the user to a random guest nick. This helps ensure that one user cannot pretend to be another user by assuming control of his nick. When a registered user with a password claims a chat room, the user can then set controls on who can enter the chat room and specify who else has control over chat room settings. A split puts the security of both nicks and chat rooms at a minor and temporary risk of hijacking.
During a netsplit, a user can temporarily gain control over a chat channel if the channel is unregistered and all user admins are disconnected during the netsplit. After the split, most servers automatically return control to the users with admin status prior to the netsplit. In some cases, if all admins are disconnected, the netsplit can result in an Internet relay chat takeover that costs the original administrators control over the channel. This is considered a grand offense and a bit of a big deal on IRC, even though starting a new channel on the service is as simple as finding an unregistered name.