Microtik: Removing ISP DNS servers

Certain Microtik routers will use ISP's DNS servers by default even if you override it to custom DNS servers.

In the Microtik console, performing a /ip dns print will show this in dynamic-servers field:

[admin@ATik-Pro-1G] /ip/dns> print
servers: 1.1.1.1
dynamic-servers: xxx.x.xxx.xx,xxx.xxx.xxx.xx <--- From ISP
use-doh-server:
verify-doh-cert: no
...
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To disable this completely, set use-peer-dns=no on your WAN interface's DHCP client:

/ip dhcp-client set 0 use-peer-dns=no
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Results:

[admin@ATik-Pro-1G] /ip/dns> /ip dns print
servers: 1.1.1.1
dynamic-servers:                             <--- No more!
use-doh-server:
verify-doh-cert: no
...
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This will ensure your custom DNS server is always used, instead of your ISP's.