If under DHCP / Networks a DNS server is not specified what will it hand out for DNS to clients?
I found that depends on your WAN settings. If that is dhcp client, the dhcp server usually issues two, the router interface ip and the ip sent with the dhcp response. That depends on what you selected in the dhcp client setup. If you left the defaults alone, it sets “use-peer-dns=yes”.
Otherwise, it issues only the ip of the router interface.