Since updating to macOS 26.4 developerbeta 2 I've been getting full loss of dns resolution. I am not running a VPN or any network extensions that I am aware of.
I'm not sure how to report this in the feedback utility as I cannot find an appropriate category for it. Happy to file it if someone can give an appropriate suggestion - the closest I could see was Wi-Fi but that wanted Wi-Fi logs for the issue, which I do not believe to be needed as this is not a Wi-Fi connectivity issue.
Running
dig example.com +short
nslookup example.com
ping example.com
Gives the following output
104.18.27.120
104.18.26.120
Server: 10.0.1.1
Address: 10.0.1.1#53 \Non-authoritative answer:
Name: example.com Address: 104.18.26.120
Name: example.com
Address: 104.18.27.120 \ping: cannot resolve example.com: Unknown host
This shows it's not an issue with my local network and that core networking is working, but something in the mDNSResponder/dns stack of macOS is failing. This causes all apps/browsers that do not implement their own DNS lookups to fail (Chrome still works).
Sometimes the issue clears after running the following commands (for a period), sometimes it does not. A restart always resolves the issue temporarily.
sudo killall -9 mDNSResponder
sudo killall -9 mDNSResponderHelper
sudo dscacheutil -flushcache
sudo ifconfig en0 down
sudo ifconfig en0 up