Both HLS and DASH support redundant streams (by adding a redundant variant URL in the HLS playlist and multiple BaseURLs in the DASH manifest). It's indeed the simplest way to have the easiest way to have a fallback client-side. If you use it, you should make sure that the player supports it, and that the retry mechanisms are rightly configured (like for instance all the MaxRetry config params in hls.js: https://github.com/video-dev/hls.js/blob/master/docs/API.md#... )
