Add support for DDR for DoH

[cyberblob]

This allows devices to get the DoH servers to use for all devices on network.

"Here is how it works: Windows starts knowing only about a plain-text DNS server (knowing only an IP address for a resolver). Hoping to encrypt its traffic, Windows sends a DNS SVCB query for “resolver.arpa”, a new special use domain name that refers to the resolver receiving the query as opposed to a name within the DNS hierarchy. If an SVCB record is returned, it carries a DoH template along with either IP address hints or additional A/AAAA records for the DoH template name."

https://techcommunity.microsoft.com/t5/networking-blog/making-doh-discoverable-introducing-ddr/ba-p/2887289

https://datatracker.ietf.org/doc/draft-ietf-add-ddr/

[ShreyasZare]

Thanks for asking. The support for DDR already exists. You just need to add the SVCB record by creating a "resolver.arpa" primary zone that is mentioned in the article and it would work.

[Hemsby]

Please could you share an example on how to create the SVCB Record in this zone. From: Shreyas Zare ***@***.***> Sent: Friday, August 18, 2023 8:56 AM To: TechnitiumSoftware/DnsServer ***@***.***> Cc: Subscribed ***@***.***> Subject: Re: [TechnitiumSoftware/DnsServer] Add support for DDR for DoH (Discussion #705) Thanks for asking. The support for DDR already exists. You just need to add the SVCB record by creating a "resolver.arpa" primary zone that is mentioned in the article and it would work. — Reply to this email directly, view it on GitHub<#705 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AISWMGVE6AMLDVN5AUEVVRLXV4N2NANCNFSM6AAAAAA3UVSVR4>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.******@***.***>>

[ShreyasZare]

Sure. Just create resolver.arpa primary zone and add the SVCB record as shown below:

The above record will add SVCB record to indicate that the client should use https://dns.quad9.net/dns-query DoH service.