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Measuring the size of Mozilla's DOH Canary Domain

Mozilla announced the creation of a "use-application-dns.net" "Canary Domain" that could be configured within ISPs to disable Firefox's default use of DNS over HTTPS. On 2019/09/21 I created a RIPE Atlas measurement to study resolvers within ISPs that had been configured to return an NXDOMAIN response. This measurement is configured to have 1000 Atlas probes query for the use-application-dns.net name once a day.

The graph below shows the results of that measurement. The vertical axis is the percentage of NXDOMAIN answers:

\(y_t = 100 \cdot \frac{number\_of\_NXDOMAINs}{number\_of\_real\_answers + number\_of\_NXDOMAINs}\)

Notes:

• I have not examined which RIPE atlases probes in the set might be hosted within the same ISP.
• I'm ignore timeouts in the data, and hence the usage of "percentage" as defined above.
• I'll update this graph "occasionally".