macOS Sonoma cannot resolve short hostnames (no dots) when there is an active interface of NETransparentProxyProvider type. I have submitted a report FB13288727, but maybe I am missing something and there is a way to fix this from our NETransparentProxyProvider code?
Normally, when you specify the search domain "example.net", the system resolver automatically adds it to the short hostnames like "testhost" (no dots). So the resulting query is "testhost.example.net". https://support.apple.com/en-il/guide/mac-help/mh141272/mac
Starting from macOS Sonoma when there is an active interface of NETransparentProxyProvider type, the system resolver tries to resolve using only the first domain from the list. Also it does not try to resolve the hostname as it is (without the search domain).
What makes this bug fatal is that Sonoma automatically adds a hidden entry like "0.5.168.192.in-addr.arpa" in the search domain list. So it tries to resolve shorthostname.0.5.168.192.in-addr.arpa, fails and does not try without the domain. So the resolution of all short hostnames always fails.
It could be easily tested with a command like "ping store" and Search Domain "apple.com"
Pre Sonoma versions: ping store PING store.apple.com (23.14.139.109): 56 data bytes...
Sonoma: ping store ping: cannot resolve store: Unknown host In reality, it tries to resolve store.0.5.168.192.in-addr.arpa and fails. It does not try to resolve store.apple.com at all. This can be seen in the traffic to the DNS server (UDP port 53).