I don’t understand what this means. I tried domain fronting and using a bare IP address, and it doesn’t work for me.
$ curl --include https://1.1.1.1/dns-query
HTTP/2 400
date: Tue, 05 Nov 2019 23:53:26 GMT
access-control-allow-origin: *
expect-ct: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
server: cloudflare
cf-ray: 5312bf478925e202-ORD
$ curl --include https://mozilla.cloudflare-dns.com/dns-query
HTTP/2 400
date: Tue, 05 Nov 2019 23:53:38 GMT
access-control-allow-origin: *
expect-ct: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
server: cloudflare
cf-ray: 5312bf90d972e216-ORD
$ curl --include https://cloudflare.com/dns-query -H 'Host: 1.1.1.1'
HTTP/2 403
server: cloudflare
date: Tue, 05 Nov 2019 23:54:09 GMT
content-type: text/html
content-length: 151
cf-ray: 5312c04ebb37ed9f-SJC
<html>
<head><title>403 Forbidden</title></head>
<body>
<center><h1>403 Forbidden</h1></center>
<hr><center>cloudflare</center>
</body>
</html>
$ dig +short cloudflare.com
198.41.214.162
198.41.215.162
$ curl --insecure --include https://198.41.215.162/dns-query -H 'Host: 1.1.1.1'
HTTP/2 403
server: cloudflare
date: Tue, 05 Nov 2019 23:54:48 GMT
content-type: text/html
content-length: 151
cf-ray: 5312c1445d389dd1-ORD
<html>
<head><title>403 Forbidden</title></head>
<body>
<center><h1>403 Forbidden</h1></center>
<hr><center>cloudflare</center>
</body>
</html>