// DNS Over HTTPS対応
user_pref("network.trr.mode", 2);
user_pref("network.trr.uri", "https://mozilla.cloudflare-dns.com/dns-query");
user_pref("network.trr.bootstrapAddress", "1.1.1.1");
network.trr.mode（数値）
DNS Over HTTPS機能の動作設定
- A value of 0 means that it is disabled and not used.
- A value of 1 that Firefox uses either native DNS or TRR depending on which is faster.
- A value of 2 uses TRR by default but will fall back to the native resolver if the name resolve fails for whatever reason.
- A value of 3 enables TRR only mode. Only TRR is used and there is no fallback.
- A value of 4 runs it in shadow mode which means that TRR is run in parallel for gathering data but that the native resolver is used.
network.trr.uri（文字列）
DNS Over HTTPSで使用するDNSサーバのURL
- Cloudflare：https://mozilla.cloudflare-dns.com/dns-query
- Google Public DNS：https://dns.google.com/
- CleanBrowsing：https://doh.cleanbrowsing.org/doh/family-filter/（https://doh.cleanbrowsing.org/doh/adult-filter/）
network.trr.bootstrapAddress（文字列）
DNSサーバのURLの名前解決を行うDNSサーバのIPアドレス
関連：
・FirefoxでDNS Over HTTPSを有効にする方法 | ハルパス
・Firefox, DNS over HTTPS and a controversial Shield Study - gHacks Tech News
