Fallback/Secondary DNS

[Generator]

Description

RethinkDNS app only uses one DNS server, in case of service issues connections will fail.
Some users have self-hosted DNS server (AdGuard Home, Pi-Hole ...), sometimes the server need maintenance or system fail, during maintenance users could use the main DNS.

Solution

Having a secondary DNS or fallback will solve the issues in case of main server failure.

[ignoramous]

Makes sense. We do plan to introduce concept of what we call a default server to which the connections would fallback upon.

That said, for DNSCrypt and DoH, servers are bootstrapped with multiple IPs where available. For example, RethinkDNS' servers are behind three Cloudflare anycast IPs and all three can and will be used in the current implementation.

[4-FLOSS-Free-Libre-Open-Source-Software]

Some users have self-hosted DNS server (AdGuard Home, Pi-Hole ...),

Would be nice to use this as default, but if can't connect for whatever reason or when you are not connected at home wifi to automatically fallback to a backup dns.

[alextenev]

Hi, Any chance for this feature to be developed?

[ignoramous]

Yes, fallback dns shipped with v054 (3 weeks ago): Configure -> Settings -> Fallback DNS

Only a limited number of fallbacks (all DoH) though:

• Rethink (zero.rethinkdns.com)
• Cloudflare (cloudflare-dns.com)
• Google (dns.google)

We plan to add Quad9 and System DNS in a future release.

Fallback is rarely needed so, a range of configuration options aren't really required. Besides, fallback DNS entries are hard-coded into the app and cannot be user modified.

rethink-app/app/src/main/java/com/celzero/bravedns/util/Constants.kt

Lines 272 to 277 in 139272a

	val DEFAULT_DNS_LIST =
	listOf(
	DefaultDnsServer(0, "Rethink", "https://zero.rethinkdns.com/dns-query", "DoH"),
	DefaultDnsServer(1, "Google", "https://dns.google.com/dns-query", "DoH"),
	DefaultDnsServer(2, "Cloudflare", "https://cloudflare-dns.com/dns-query", "DoH")
	)

[NanashiTheNameless]

Consider adding the ability to revert to the old behavior for security reasons...

[ignoramous]

What security reasons do you think warrant removal of a fallback? I can see the privacy angle.

Perhaps, we should add None as an option that disables fallback.

[NanashiTheNameless]

Exactly my point, just a simple "none" option edit: security as in ensuring DNS queries ONLY go through my existing DNS firewall (NextDNS) thats why im sadly currently stuck with nebulo

[ignoramous]

security as in ensuring DNS queries ONLY go through my existing DNS firewall (NextDNS)

None has been there as "Fallback" for some 8 months now.

Fallback is rarely needed so, a range of configuration options aren't really required. Besides, fallback DNS entries are hard-coded into the app and cannot be user modified.

golang/go#8877 (comment)