NetworkManager online check causes many DNS requests #2100
Description
It seems that the NetworkManager's online check creates multiple queries to resolve our connectivity check server checkonline.home-assistant.io. A single nmcli networking connectivity check caused 8 queries on my test system.
It seems that this is caused by the multiple veth interfaces generated by Docker:
# nmcli general logging level DEBUG domains CONCHECK
# journalctl -u NetworkManager -o cat -f &
# <debug> [1661977513.5161] connectivity: (docker0,IPv6,1091) check completed: LIMITED; check failed: (7) Error
<debug> [1661977513.5163] connectivity: (vethf7179ba,IPv6,1097) check completed: LIMITED; check failed: (7) Error
<debug> [1661977513.5165] connectivity: (vetheff08b7,IPv6,1105) check completed: LIMITED; check failed: (7) Error
<debug> [1661977513.5166] connectivity: (veth46f861f,IPv6,1101) check completed: LIMITED; check failed: (7) Error
<debug> [1661977513.5168] connectivity: (veth8c00d89,IPv6,1095) check completed: LIMITED; check failed: (7) Error
<debug> [1661977513.5170] connectivity: (veth93dd0f7,IPv6,1099) check completed: LIMITED; check failed: (7) Error
<debug> [1661977513.5172] connectivity: (hassio,IPv6,1093) check completed: LIMITED; check failed: (7) Error
<debug> [1661977513.5173] connectivity: (vethdaf3f07,IPv6,1103) check completed: LIMITED; check failed: (7) Error
<debug> [1661977513.5311] connectivity: (enp8s0,IPv4,1088) check completed: FULL; expected response
<debug> [1661977513.5376] connectivity: (enp8s0,IPv6,1089) check completed: FULL; expected response
# nmcli networking connectivity check
full
# <debug> [1661977565.4524] connectivity: (enp8s0,IPv4,1106) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4525] connectivity: (enp8s0,IPv6,1107) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4525] connectivity: (docker0,IPv4,1108) skip connectivity check due to no global route configured
<debug> [1661977565.4525] connectivity: (docker0,IPv6,1109) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4525] connectivity: (hassio,IPv4,1110) skip connectivity check due to no global route configured
<debug> [1661977565.4526] connectivity: (hassio,IPv6,1111) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4526] connectivity: (veth8c00d89,IPv4,1112) skip connectivity check due to no IP address configured
<debug> [1661977565.4527] connectivity: (veth8c00d89,IPv6,1113) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4527] connectivity: (vethf7179ba,IPv4,1114) skip connectivity check due to no IP address configured
<debug> [1661977565.4527] connectivity: (vethf7179ba,IPv6,1115) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4527] connectivity: (veth93dd0f7,IPv4,1116) skip connectivity check due to no IP address configured
<debug> [1661977565.4528] connectivity: (veth93dd0f7,IPv6,1117) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4528] connectivity: (veth46f861f,IPv4,1118) skip connectivity check due to no IP address configured
<debug> [1661977565.4528] connectivity: (veth46f861f,IPv6,1119) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4529] connectivity: (vethdaf3f07,IPv4,1120) skip connectivity check due to no IP address configured
<debug> [1661977565.4529] connectivity: (vethdaf3f07,IPv6,1121) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4529] connectivity: (vetheff08b7,IPv4,1122) skip connectivity check due to no IP address configured
<debug> [1661977565.4530] connectivity: (vetheff08b7,IPv6,1123) start request to 'http://checkonline.home-assistant.io/online.txt' (try resolving 'checkonline.home-assistant.io' using systemd-resolved)
<debug> [1661977565.4530] connectivity: (docker0,IPv4,1108) check completed: LIMITED; no global route configured
<debug> [1661977565.4530] connectivity: (hassio,IPv4,1110) check completed: LIMITED; no global route configured
<debug> [1661977565.4530] connectivity: (veth8c00d89,IPv4,1112) check completed: NONE; no IP address configured
<debug> [1661977565.4530] connectivity: (vethf7179ba,IPv4,1114) check completed: NONE; no IP address configured
<debug> [1661977565.4530] connectivity: (veth93dd0f7,IPv4,1116) check completed: NONE; no IP address configured
<debug> [1661977565.4530] connectivity: (veth46f861f,IPv4,1118) check completed: NONE; no IP address configured
<debug> [1661977565.4530] connectivity: (vethdaf3f07,IPv4,1120) check completed: NONE; no IP address configured
<debug> [1661977565.4530] connectivity: (vetheff08b7,IPv4,1122) check completed: NONE; no IP address configured
<debug> [1661977565.4576] connectivity: (docker0,IPv6,1109) can't resolve a name via systemd-resolved: GDBus.Error:org.freedesktop.resolve1.NoNameServers: No appropriate name servers or networks for name found
<debug> [1661977565.4577] connectivity: (hassio,IPv6,1111) can't resolve a name via systemd-resolved: GDBus.Error:org.freedesktop.resolve1.NoNameServers: No appropriate name servers or networks for name found
<debug> [1661977565.4582] connectivity: (veth8c00d89,IPv6,1113) can't resolve a name via systemd-resolved: GDBus.Error:org.freedesktop.resolve1.NoNameServers: No appropriate name servers or networks for name found
<debug> [1661977565.4583] connectivity: (vethf7179ba,IPv6,1115) can't resolve a name via systemd-resolved: GDBus.Error:org.freedesktop.resolve1.NoNameServers: No appropriate name servers or networks for name found
<debug> [1661977565.4590] connectivity: (docker0,IPv6,1109) check completed: LIMITED; check failed: (7) Error
<debug> [1661977565.4599] connectivity: (veth8c00d89,IPv6,1113) check completed: LIMITED; check failed: (7) Error
<debug> [1661977565.4608] connectivity: (hassio,IPv6,1111) check completed: LIMITED; check failed: (7) Error
<debug> [1661977565.4613] connectivity: (vethf7179ba,IPv6,1115) check completed: LIMITED; check failed: (7) Error
<debug> [1661977565.4617] connectivity: (veth93dd0f7,IPv6,1117) can't resolve a name via systemd-resolved: GDBus.Error:org.freedesktop.resolve1.NoNameServers: No appropriate name servers or networks for name found
<debug> [1661977565.4622] connectivity: (veth46f861f,IPv6,1119) can't resolve a name via systemd-resolved: GDBus.Error:org.freedesktop.resolve1.NoNameServers: No appropriate name servers or networks for name found
<debug> [1661977565.4623] connectivity: (vethdaf3f07,IPv6,1121) can't resolve a name via systemd-resolved: GDBus.Error:org.freedesktop.resolve1.NoNameServers: No appropriate name servers or networks for name found
<debug> [1661977565.4623] connectivity: (vetheff08b7,IPv6,1123) can't resolve a name via systemd-resolved: GDBus.Error:org.freedesktop.resolve1.NoNameServers: No appropriate name servers or networks for name found
<debug> [1661977565.4636] connectivity: (veth46f861f,IPv6,1119) check completed: LIMITED; check failed: (7) Error
<debug> [1661977565.4639] connectivity: (vethdaf3f07,IPv6,1121) check completed: LIMITED; check failed: (7) Error
<debug> [1661977565.4644] connectivity: (vetheff08b7,IPv6,1123) check completed: LIMITED; check failed: (7) Error
<debug> [1661977565.4649] connectivity: (veth93dd0f7,IPv6,1117) check completed: LIMITED; check failed: (7) Error
<debug> [1661977565.4786] connectivity: (enp8s0,IPv4,1106) check completed: FULL; expected response
<debug> [1661977565.4800] connectivity: (enp8s0,IPv6,1107) check completed: FULL; expected response