How to setup Cloudflare DNS-over-HTTPS (DoH) cache on MikroTik RouterOS router

Compared to standard UDP DNS, DNS-over-HTTPS (DoH) provides the huge advantage that – due to it being encrypted, someone able to sniff the traffic will not be able to determine what domain names are being used.

However, consider the disadvantage that the latency of resolving a domain name is significantly larger with DoH – however, setting up the MikroTik router as DNS cache will significantly reduce the overall DNS latency, at least for cached domain names.

The following list of RouterOS commands will setup the internal DNS server as a DNS cache running on DNS-over-HTTPS.

First, download CA certificates onto the router in order to be able to verify CloudFlare’s HTTPS certificates:

/tool fetch url=https://curl.se/ca/cacert.pem

Wait for it to finish downloading, e.g.

[[email protected]] > /tool fetch url=https://curl.se/ca/cacert.pem
      status: finished
  downloaded: 210KiBz pause]
       total: 210KiB
    duration: 1s

Now import the file and setup the DNS server:

/certificate import file-name=cacert.pem passphrase=""
/ip dns set allow-remote-requests=yes cache-size=8192KiB max-concurrent-queries=1000 max-concurrent-tcp-sessions=2000 servers=1.1.1.1 use-doh-server=https://cloudflare-dns.com/dns-query verify-doh-cert=yes