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I have a service running on a static IP within my LAN and PiHole specifies a domain name for that IP address. For example, my.server.com === 192.168.1.10. Prior to Big Sur, this worked fine. Now, it keeps reverting to whatever global DNS records specify instead of the address provided by PiHole. If I clear the DNS cache with sudo killall -HUP mDNSResponder the name will resolve to the desired IP address for a very short time (less than a minute or two) and then revert to the global records. Short of using /etc/hosts how can I get Big Sur to respect PiHole's DNS?

Michael Prescott
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  • I don't think this is strictly, directly a Big Sur effect. I think what may be happening is systems on our LAN running Big Sur are causing a LOT more traffic now. Lot's a connections to Apple's servers, constantly. This has overwhelmed the machine running PiHole, causing sluggish responses. Our router fails over to a non-pihole DNS if PiHole cannot resolve quickly. If I remove the failover DNS, the static IP override will stick. So, I need to determine why Big Sur is creating so much more traffic or upgrade our PiHole. – Michael Prescott Nov 16 '20 at 01:41
  • And it just lost the static IP again, despite removing the failover DNS from the router. It took quite a while longer this time. So, from the router perspective and from PiHole, my.server.com === 192.168.1.10 and there is no alternative IP; however, Big Sur seemingly has it "in mind" that it should trust a more authoritative upstream DNS instead of local configuration. Interestingly, ad blocking in general works. It's just this one custom override failing. – Michael Prescott Nov 16 '20 at 03:34
  • Last update. I'm going to change the upstream records or use /etc/hosts. `brctl log -w --shorten` and other network tools hint that everything you do on macOS is now chattering with Apple servers. You open an app, chatter, you merely start to save a file even if you cancel, chatter. Search your local machine, chatter, every keypress ping ping ping. Whether or not macOS has been doing this all along, I dunno, but it's so much now that it's having a significant effect on my PiHole service, and that seemingly causes Big Sur to use another means of resolving domain names. – Michael Prescott Nov 16 '20 at 04:07
  • Did you see this also with Catalina? Also, are any of the Apple servers in piholes blacklist? – learning2learn Aug 17 '21 at 14:29

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