参考文献

server to initially resolve the server's host name into an address. Alternative strategies a client might employ include 1) making the initial resolution part of the configuration, 2) IP-based URIs and corresponding IP-based certificates for HTTPS, or 3) resolving the DNS API server's hostname via traditional DNS or another DoH server while still authenticating the resulting connection via HTTPS.

HTTP [RFC7230] is a stateless application-level protocol, and therefore DoH implementations do not provide stateful ordering guarantees between different requests. DoH cannot be used as a transport for other protocols that require strict ordering.

A DoH server is allowed to answer queries with any valid DNS response. For example, a valid DNS response might have the TC (truncation) bit set in the DNS header to indicate that the server was not able to retrieve a full answer for the query but is providing the best answer it could get. A DoH server can reply to queries with an HTTP error for queries that it cannot fulfill. In this same example, a DoH server could use an HTTP error instead of a non-error response that has the TC bit set.

Many extensions to DNS, using [RFC6891], have been defined over the years. Extensions that are specific to the choice of transport, such as [RFC7828], are not applicable to DoH.

11. References

11.1. Normative References

[RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, November 1987, [https://www.rfc-editor.org/info/rfc1035](https://www.rfc-editor.org/info/rfc1035).

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, [https://www.rfc-editor.org/info/rfc2119](https://www.rfc-editor.org/info/rfc2119).

[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998, [https://www.rfc-editor.org/info/rfc2308](https://www.rfc-editor.org/info/rfc2308).



[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, [https://www.rfc-editor.org/info/rfc4648](https://www.rfc-editor.org/info/rfc4648).

[RFC6265] Barth, A., "HTTP State Management Mechanism", RFC 6265, DOI 10.17487/RFC6265, April 2011, [https://www.rfc-editor.org/info/rfc6265](https://www.rfc-editor.org/info/rfc6265).

[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M., and D. Orchard, "URI Template", RFC 6570, DOI 10.17487/RFC6570, March 2012, [https://www.rfc-editor.org/info/rfc6570](https://www.rfc-editor.org/info/rfc6570).

[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, [https://www.rfc-editor.org/info/rfc7230](https://www.rfc-editor.org/info/rfc7230).

[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, June 2014, [https://www.rfc-editor.org/info/rfc7231](https://www.rfc-editor.org/info/rfc7231).

[RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests", RFC 7232, DOI 10.17487/RFC7232, June 2014, [https://www.rfc-editor.org/info/rfc7232](https://www.rfc-editor.org/info/rfc7232).

[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching", RFC 7234, DOI 10.17487/RFC7234, June 2014, [https://www.rfc-editor.org/info/rfc7234](https://www.rfc-editor.org/info/rfc7234).

[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Authentication", RFC 7235, DOI 10.17487/RFC7235, June 2014, [https://www.rfc-editor.org/info/rfc7235](https://www.rfc-editor.org/info/rfc7235).

[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/RFC7540, May 2015, [https://www.rfc-editor.org/info/rfc7540](https://www.rfc-editor.org/info/rfc7540).

[RFC7541] Peon, R. and H. Ruellan, "HPACK: Header Compression for HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015, [https://www.rfc-editor.org/info/rfc7541](https://www.rfc-editor.org/info/rfc7541).



[RFC7626] Bortzmeyer, S., "DNS Privacy Considerations", RFC 7626, DOI 10.17487/RFC7626, August 2015, [https://www.rfc-editor.org/info/rfc7626](https://www.rfc-editor.org/info/rfc7626).

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, [https://www.rfc-editor.org/info/rfc8174](https://www.rfc-editor.org/info/rfc8174).

[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, [https://www.rfc-editor.org/info/rfc8446](https://www.rfc-editor.org/info/rfc8446).

11.2. Informative References

[FETCH] "Fetch Living Standard", August 2018, [https://fetch.spec.whatwg.org/](https://fetch.spec.whatwg.org/).

[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/RFC2818, May 2000, [https://www.rfc-editor.org/info/rfc2818](https://www.rfc-editor.org/info/rfc2818).

[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, [https://www.rfc-editor.org/info/rfc5280](https://www.rfc-editor.org/info/rfc5280).

[RFC5861] Nottingham, M., "HTTP Cache-Control Extensions for Stale Content", RFC 5861, DOI 10.17487/RFC5861, May 2010, [https://www.rfc-editor.org/info/rfc5861](https://www.rfc-editor.org/info/rfc5861).

[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van Beijnum, "DNS64: DNS Extensions for Network Address Translation from IPv6 Clients to IPv4 Servers", RFC 6147, DOI 10.17487/RFC6147, April 2011, [https://www.rfc-editor.org/info/rfc6147](https://www.rfc-editor.org/info/rfc6147).

[RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms for DNS (EDNS(0))", STD 75, RFC 6891, DOI 10.17487/RFC6891, April 2013, [https://www.rfc-editor.org/info/rfc6891](https://www.rfc-editor.org/info/rfc6891).

[RFC6950] Peterson, J., Kolkman, O., Tschofenig, H., and B. Aboba, "Architectural Considerations on Application Features in the DNS", RFC 6950, DOI 10.17487/RFC6950, October 2013, [https://www.rfc-editor.org/info/rfc6950](https://www.rfc-editor.org/info/rfc6950).



[RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. Adams, "X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP", RFC 6960, DOI 10.17487/RFC6960, June 2013, [https://www.rfc-editor.org/info/rfc6960](https://www.rfc-editor.org/info/rfc6960).