Backup ingest server

YouTube hands out two ingest URLs for a live stream, a primary and a backup, both taking the same stream key. An encoder that supports redundant output sends the same feed to both at once. If the primary path fails, whether the connection drops or the encoder falls over, YouTube keeps going on the backup and viewers get a brief wobble instead of a dead stream. It costs you double the upload bandwidth, so check your headroom before switching it on. Sending only to the backup address with nothing on the primary gives you no redundancy at all.