UDP broadcast packets across subnets

Yes, and no. It’s actually do-able, so long as the intervening routers don’t have no ip directed-broadcasts or similar configured. However these days that’s the default because allowing normal broadcasts to traverse routers is a DoS problem. If you really want to broadcast across subnets then you should be using IP Multicast instead. That still … Read more

TCP stream vs UDP message

The interface/API presented to you the user(programmer) of these protocols are: UDP Message oriented, you have an API (send/recv and similar) that provide you with the ability to send one datagram, and receive one datagram. 1 send() call results in 1 datagram sent, and 1 recv() call will recieve exactly 1 datagram. TCP Stream oriented, … Read more

Valid characters of a hostname?

Checkout this wiki, specifically the section Restrictions on valid host names Hostnames are composed of series of labels concatenated with dots, as are all domain names. For example, “en.wikipedia.org” is a hostname. Each label must be between 1 and 63 characters long, and the entire hostname (including the delimiting dots but not a trailing dot) … Read more

TCP vs UDP on video stream

Drawbacks of using TCP for live video: As you mentioned, TCP buffers the unacknowledged segments for every client. In some cases this is undesirable, such as TCP streaming for very popular live events: your list of simultaneous clients (and buffering requirements) are large in this case. Pre-recorded video-casts typically don’t have as much of a … Read more