PasTim wrote: 
> Being somewhat ignorant about such things, how can local Powerline
> adapters affect DNS?  Can other local network factors affect this?  Does
> the external DNS server used make any difference?

I don't really know either, but he seemed to know what he was talking
about.

What he is saying is that with the akamai CDN (the one we use for live
streams because it is baked into the url in menu.opml) the time-to-live
in DNS responses is often set to zero. This means that the local
handling of DNS lookups in the OS, router and ISP DNS server or whatever
(I don't know how this stuff works) must do a full external DNS lookup
through to the akamai DNS server for every HLS HTTP request rather than
using a cached address. So for every HLS chunk and playlist update
request (these both happen for every chunk on average - every 6.4
seconds with live streams), a full DNS request and response is required
before the HTTP GET request can be made.

It's still not a lot of traffic IMHO, but I guess if there are network
issues causing a lot of latency on each DNS lookup it could slow things
down too much.

I've had a look at the network traffic of LMS playing the HLS streams on
a windows PC and I'm not actually seeing all those external DNS requests
- they appear to be about every 20 seconds. So maybe the problem at the
akamai CDN he's talking about is only intermittently there. Maybe when
the servers get very busy they do this to spread the load evenly across
the servers or something.

This problem, if it really exists, could be mitigated by the plugin
using either persistent HTTP connections (I don't know how that should
be done, and don't think it is a good thing to do), or doing it's own
DNS lookup and then using the same IP address directly for a large
number of HTTP requests. I think I can see how that could be done...


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