WAN DNS not propagated to DHCP Clients

General discussion
6

It probably bears down to the hybrid deployments in OpenWrt and the patchset in TOS:

OpenWrt

  • hybrid DHCPv4/DNS via dnsmasq as default
  • DHCPv6 via odhcpd as default
  • (L)UCI for configuration, another hybrid since part of it manipulating the UCI network section and another part the UCI dhcp section

TOS

  • DHCPv4 via dnsmasq as default
  • DHCPv6 via odhcpd as default
  • DNS via kresd by default (dnsmasq for DNS turned off)
  • Foris for configuration (which not always aligns with UCI) with underlying resolver for DNS configuration

By default in OpenWrt the ISP’s DNS sever is set and can be controlled (peerdns | dns) via (L)UCI in the network section. This glues/ties it with dnsmasq and eventually propagates the DNS server to clients.

Since dnsmasq's DNS functionality is turned off in TOS not every thing done in LuCI applies the same as in OpenWrt.

One can get easily tangled up in all of this hybrid jungle and start wondering what is what. For my part:

  • not using LuCI or Foris for any network/dns/dhcp configuration
  • removed dnsmasq
  • utilise odhcpd for DHCPv4|6 which propagates the local DNS resolver instance to clients
  • utilise undbound as local DNS resolver instance that does not listen globally but only on the lo and each other dhcp subnet