User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_3) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0.3 Safari/605.1.15

Steps to reproduce:

1. Install and launch Firefox nightly
2. Set network.trr.bootstrapAddress to 68.183.200.129
3. Set network.trr.custom_uri to https://rfc8484.com/dns-query
4. Set network.trr.mode to 3
5. Set network.trr.uri to https://rfc8484.com/dns-query
6. Attempt to load any webpage - will fail with a server not found error

Restarting Firefox will not resolve the issue - with network.trr.mode set to 3 it is impossible to browse even with the bootstrap address set. Attempted without bootstrap address (step 2) and the issue persists.

Actual results:

Firefox fails to do DNS lookups using RFC8484 (DNS over HTTP)

Expected results:

Firefox should be able to query the name server and browse webpages.

Lower priority for mode 3.

(In reply to mgamble from comment #0)

Firefox fails to do DNS lookups using RFC8484 (DNS over HTTP)

It works for me. Can you provide some logging so we can see why it doesn't on your machine?

https://developer.mozilla.org/en-US/docs/Mozilla/Debugging/HTTP_logging

Closing this as the reporter never provided the logs.

One reason for which network.trr.mode=3 does not work out of the box is the absence of a default value for network.trr.bootstrapaddress

What about having a default server for network.trr.bootstrapaddress?

(In reply to monperrus from comment #4)

One reason for which network.trr.mode=3 does not work out of the box is the absence of a default value for network.trr.bootstrapaddress

What about having a default server for network.trr.bootstrapaddress?

Starting with Firefox 74 (bug 1552176) setting the bootstrap address is no longer mandatory - the browser will simply bootstrap itself using regular DNS, unless the DoH server domain can't be resolved. In that case you do need to set it.

Since we haven't yet shipped mode3 UI, you can consider this feature to be alpha/beta quality - you may use it, but expect bugs and/or a bad user experience. This will probably change in the near future.

In any case, the problem with the bootstrap address is that if you set it to the wrong IP (for example, to Cloudflare's 104.16.248.249 and use https://dns.google/dns-query as the URI) then you'll get a certificate mismatch, and it won't work, so you have to keep them in sync. Also, IPs change sometimes, so it's not the best idea to hardcode them in the browser.

Starting with Firefox 74 (bug 1552176) setting the bootstrap address is no longer mandatory - the browser will simply bootstrap itself using regular DNS, unless the DoH server domain can't be resolved.

Excellent news!