Hello DATA,

For *) I can't say definitely, but from what I know, there's no way to make a reliable ordered UDP connection, since UDP is an inherently unreliable protocol (hence it's name) and all reliability, sequencing and reordering is usually to be done by the application.

For 2), out-of-band data for SOCK_STREAM is a TCP feature; when your application needs to send something that is not related to the current stream of data, say, some kind of flag indicating urgent action to the other side, it can do so with this feature (it's also called TCP URGENT), on the same socket.

And *) is the easiest - these numbers are man page sections. Often, there are several entries in the mandb on a word, so to pull a description of a function as opposed, say, to a command-line utility, you call "man 2 socket" instead of "man socket" to be sure what sectyion of man database your docs come from.

Hope this helps somewhat