So, I run AdGuard Home, similar to Pi hole, and obviously I get the same issue with thousands of logging requests from Roku TV. I experimented with different ways of responding to these requests and have discovered the following about these responses:
1) NXDOMAIN, causes the device to resend a DNS request every 10 seconds (at least, can be more)
2) NOERROR, same as 1.
3) 0.0.0.0, same as 1
4) 127.0.0.1 same as 1
5) SERVFAIL, causes 2 requests to be sent every 30 seconds
6) REFUSED, same as 5
In addition to this methods 1-4 can result in large numbers of re-requests when actually using the device. I see runs of 10 to 30 requests over a few seconds when switching channels etc, however this is not the case with methods 5 & 6, I only ever see pairs of requests at a much lower frequency.
So, currently I'm using REFUSED as my response, and I think this best represents whats happening.
On AdGuard Home, this can be implemented in the custom filtering section with the entry:
||logs.roku.com^^$important,dnsrewrite=REFUSED;;
I'm sure its something similar on PiHole.
This has no impact on the performance of the device (Roku TV Express), and its actually the fastest of all my streaming devices in terms of responsiveness. Just block and forget about it...
N.B. You will only see this behaviour if you block all but your own outbound DNS requests, as the Roku will use 8.8.8.8 and 8.8.4.4 as a fallback for any 'failed' requests.
