draft-ietf-doh-dns-over-https-11.txt   draft-ietf-doh-dns-over-https-12.txt 
Network Working Group P. Hoffman Network Working Group P. Hoffman
Internet-Draft ICANN Internet-Draft ICANN
Intended status: Standards Track P. McManus Intended status: Standards Track P. McManus
Expires: December 17, 2018 Mozilla Expires: December 29, 2018 Mozilla
June 15, 2018 June 27, 2018
DNS Queries over HTTPS (DoH) DNS Queries over HTTPS (DoH)
draft-ietf-doh-dns-over-https-11 draft-ietf-doh-dns-over-https-12
Abstract Abstract
This document describes how to make DNS queries over HTTPS. This document describes how to make DNS queries over HTTPS.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 17, 2018. This Internet-Draft will expire on December 29, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 26 skipping to change at page 2, line 26
5.2.1. Handling DNS and HTTP Errors . . . . . . . . . . . . 7 5.2.1. Handling DNS and HTTP Errors . . . . . . . . . . . . 7
5.2.2. HTTP Response Example . . . . . . . . . . . . . . . . 7 5.2.2. HTTP Response Example . . . . . . . . . . . . . . . . 7
6. HTTP Integration . . . . . . . . . . . . . . . . . . . . . . 8 6. HTTP Integration . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Cache Interaction . . . . . . . . . . . . . . . . . . . . 8 6.1. Cache Interaction . . . . . . . . . . . . . . . . . . . . 8
6.2. HTTP/2 . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.2. HTTP/2 . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.3. Server Push . . . . . . . . . . . . . . . . . . . . . . . 10 6.3. Server Push . . . . . . . . . . . . . . . . . . . . . . . 10
6.4. Content Negotiation . . . . . . . . . . . . . . . . . . . 10 6.4. Content Negotiation . . . . . . . . . . . . . . . . . . . 10
7. Definition of the application/dns-message media type . . . . 10 7. Definition of the application/dns-message media type . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8.1. Registration of application/dns-message Media Type . . . 11 8.1. Registration of application/dns-message Media Type . . . 11
9. Security Considerations . . . . . . . . . . . . . . . . . . . 13 9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 13
10. Operational Considerations . . . . . . . . . . . . . . . . . 13 9.1. On The Wire . . . . . . . . . . . . . . . . . . . . . . . 13
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.2. In The Server . . . . . . . . . . . . . . . . . . . . . . 13
11.1. Normative References . . . . . . . . . . . . . . . . . . 15 10. Security Considerations . . . . . . . . . . . . . . . . . . . 15
11.2. Informative References . . . . . . . . . . . . . . . . . 16 11. Operational Considerations . . . . . . . . . . . . . . . . . 15
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 17 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
Previous Work on DNS over HTTP or in Other Formats . . . . . . . 18 12.1. Normative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 12.2. Informative References . . . . . . . . . . . . . . . . . 18
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 20
Previous Work on DNS over HTTP or in Other Formats . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
This document defines a specific protocol for sending DNS [RFC1035] This document defines a specific protocol for sending DNS [RFC1035]
queries and getting DNS responses over HTTP [RFC7540] using https queries and getting DNS responses over HTTP [RFC7540] using https
URIs (and therefore TLS [RFC5246] security for integrity and URIs (and therefore TLS [RFC5246] security for integrity and
confidentiality). Each DNS query-response pair is mapped into a HTTP confidentiality). Each DNS query-response pair is mapped into a HTTP
exchange. exchange.
The described approach is more than a tunnel over HTTP. It The described approach is more than a tunnel over HTTP. It
skipping to change at page 8, line 20 skipping to change at page 8, line 20
<64 bytes represented by the following hex encoding> <64 bytes represented by the following hex encoding>
00 00 81 80 00 01 00 01 00 00 00 00 03 77 77 77 00 00 81 80 00 01 00 01 00 00 00 00 03 77 77 77
07 65 78 61 6d 70 6c 65 03 63 6f 6d 00 00 01 00 07 65 78 61 6d 70 6c 65 03 63 6f 6d 00 00 01 00
01 03 77 77 77 07 65 78 61 6d 70 6c 65 03 63 6f 01 03 77 77 77 07 65 78 61 6d 70 6c 65 03 63 6f
6d 00 00 01 00 01 00 00 00 80 00 04 C0 00 02 01 6d 00 00 01 00 01 00 00 00 80 00 04 C0 00 02 01
6. HTTP Integration 6. HTTP Integration
This protocol MUST be used with the https scheme URI [RFC7230]. This protocol MUST be used with the https scheme URI [RFC7230].
Section 9 and Section 10 discuss additional considerations for the
integration with HTTP.
6.1. Cache Interaction 6.1. Cache Interaction
A DoH exchange can pass through a hierarchy of caches that include A DoH exchange can pass through a hierarchy of caches that include
both HTTP and DNS specific caches. These caches may exist beteen the both HTTP and DNS specific caches. These caches may exist beteen the
DoH server and client, or on the DoH client itself. HTTP caches are DoH server and client, or on the DoH client itself. HTTP caches are
by design generic; that is, they do not understand this protocol. by design generic; that is, they do not understand this protocol.
Even if a DoH client has modified its cache implementation to be Even if a DoH client has modified its cache implementation to be
aware of DoH semantics, it does not follow that all upstream caches aware of DoH semantics, it does not follow that all upstream caches
(for example, inline proxies, server-side gateways and Content (for example, inline proxies, server-side gateways and Content
Delivery Networks) will be. Delivery Networks) will be.
skipping to change at page 10, line 41 skipping to change at page 10, line 41
MUST support the "application/dns-message" media type. Other media MUST support the "application/dns-message" media type. Other media
types MAY be used as defined by HTTP Content Negotiation ([RFC7231] types MAY be used as defined by HTTP Content Negotiation ([RFC7231]
Section 3.4). Those media types MUST be flexible enough to express Section 3.4). Those media types MUST be flexible enough to express
every DNS query that would normally be sent in DNS over UDP every DNS query that would normally be sent in DNS over UDP
(including queries and responses that use DNS extensions, but not (including queries and responses that use DNS extensions, but not
those that require multiple responses). those that require multiple responses).
7. Definition of the application/dns-message media type 7. Definition of the application/dns-message media type
The data payload for the application/dns-message media type is a The data payload for the application/dns-message media type is a
single message of the DNS on-the-wire format defined in section 4.2.1 single message of the DNS on-the-wire format defined in Section 4.2.1
of [RFC1035]. The format was originally for DNS over UDP. Although of [RFC1035]. The format was originally for DNS over UDP. Although
[RFC1035] says "Messages carried by UDP are restricted to 512 bytes", [RFC1035] says "Messages carried by UDP are restricted to 512 bytes",
that was later updated by [RFC6891]. This media type restricts the that was later updated by [RFC6891]. This media type restricts the
maximum size of the DNS message to 65535 bytes. Note that the wire maximum size of the DNS message to 65535 bytes. Note that the wire
format used in this media type is different than the wire format used format used in this media type is different than the wire format used
in [RFC7858] (which uses the format defined in section 4.2.2 of in [RFC7858] (which uses the format defined in Section 4.2.2 of
[RFC1035]). [RFC1035]).
DoH clients using this media type MAY have one or more EDNS options DoH clients using this media type MAY have one or more EDNS options
[RFC6891] in the request. DoH servers using this media type MUST [RFC6891] in the request. DoH servers using this media type MUST
ignore the value given for the EDNS UDP payload size in DNS requests. ignore the value given for the EDNS UDP payload size in DNS requests.
When using the GET method, the data payload for this media type MUST When using the GET method, the data payload for this media type MUST
be encoded with base64url [RFC4648] and then provided as a variable be encoded with base64url [RFC4648] and then provided as a variable
named "dns" to the URI Template expansion. Padding characters for named "dns" to the URI Template expansion. Padding characters for
base64url MUST NOT be included. base64url MUST NOT be included.
skipping to change at page 13, line 5 skipping to change at page 13, line 5
Paul Hoffman, paul.hoffman@icann.org Paul Hoffman, paul.hoffman@icann.org
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: n/a Restrictions on usage: n/a
Author: Paul Hoffman, paul.hoffman@icann.org Author: Paul Hoffman, paul.hoffman@icann.org
Change controller: IESG Change controller: IESG
9. Security Considerations 9. Privacy Considerations
[RFC7626] discusses DNS Privacy Considerations in both "On the wire"
(Section 2.4), and "In the server" (Section 2.5) contexts. This is
also a useful framing for DoH's privacy considerations.
9.1. On The Wire
DoH encrypts DNS traffic and requires authentication of the server.
This mitigates both passive surveillance [RFC7258] and active attacks
that attempt to divert DNS traffic to rogue servers ([RFC7626]
Section 2.5.1). DNS over TLS [RFC7858] provides similar protections,
while direct UDP and TCP based transports are vulnerable to this
class of attack.
Additionally, the use of the HTTPS default port 443 and the ability
to mix DoH traffic with other HTTPS traffic on the same connection
can deter unprivileged on-path devices from interfering with DNS
operations and make DNS traffic analysis more difficult.
9.2. In The Server
The DNS wire format [RFC1035] contains no client identifiers, however
various transports of DNS queries and responses do provide data that
can be used to correlate requests. HTTPS presents new considerations
for correlation such as explicit HTTP cookies and implicit
fingerprinting of the unique set and ordering of HTTP request
headers.
A DoH implementation is built on IP, TCP, TLS, and HTTP. Each layer
contains one or more common features that can be used to correlate
queries to the same identity. DNS transports will generally carry
the same privacy properties of the layers used to implement them.
For example, the properties of IP, TCP, and TLS apply to DNS over TLS
implementations.
The privacy considerations of using the HTTPS layer in DoH are
incremental to those of DNS over TLS. DoH is not known to introduce
new concerns beyond those associated with HTTPS.
At the IP level, the client address provides obvious correlation
information. This can be mitigated by use of a NAT, proxy, VPN, or
simple address rotation over time. It may be aggravated by use of a
DNS server that can correlate real-time addressing information with
other personal identifiers, such as when a DNS server and DHCP server
are operated by the same entity.
DNS implementations that use one TCP connection for multiple DNS
requests directly group those requests. Long lived connections have
better performance behaviors than short lived connections, but group
more requests. TCP-based solutions may also seek performance through
the use of TCP Fast Open [RFC7413]. The cookies used in TCP Fast
Open allow servers to correlate TCP sessions.
TLS based implementations often achieve better handshake performance
through the use of some form of session resumption mechanism such as
session tickets [RFC5077]. Session resumption creates trivial
mechanisms for a server to correlate TLS connections together.
HTTP's feature set can also be used for identification and tracking
in a number of different ways. For example, authentication request
header fields explicitly identify profiles in use, and HTTP Cookies
are designed as an explicit state tracking mechanism between the
client and serving site and often are used as an authentication
mechanism.
Additionally, the User-Agent and Accept-Language request header
fields often convey specific information about the client version or
locale. This facilitates content negotiation and operational work-
arounds for implementation bugs. Request header fields that control
caching can expose state information about a subset of the client's
history. Mixing DoH requests with other HTTP requests on the same
connection also provides an opportunity for richer data correlation.
The DoH protocol design allows applications to fully leverage the
HTTP ecosystem, including features that are not enumerated here.
Utilizing the full set of HTTP features enables DoH to be more than
an HTTP tunnel, but at the cost of opening up implementations to the
full set of privacy considerations of HTTP.
Implementations of DoH clients and servers need to consider the
benefit and privacy impact of these features, and their deployment
context, when deciding whether or not to enable them.
Implementations are advised to expose the minimal set of data needed
to achieve the desired feature set.
Determining whether or not a DoH implementation requires HTTP cookie
[RFC6265] support is particularly important because HTTP cookies are
the primary state tracking mechanism in HTTP. HTTP Cookies SHOULD
NOT be accepted by DOH clients unless they are explicitly required by
a use case.
10. Security Considerations
Running DNS over HTTPS relies on the security of the underlying HTTP Running DNS over HTTPS relies on the security of the underlying HTTP
transport. This mitigates classic amplification attacks for UDP- transport. This mitigates classic amplification attacks for UDP-
based DNS. Implementations utilizing HTTP/2 benefit from the TLS based DNS. Implementations utilizing HTTP/2 benefit from the TLS
profile defined in [RFC7540] Section 9.2. profile defined in [RFC7540] Section 9.2.
Session level encryption has well known weaknesses with respect to Session level encryption has well known weaknesses with respect to
traffic analysis which might be particularly acute when dealing with traffic analysis which might be particularly acute when dealing with
DNS queries. HTTP/2 provides further advice about the use of DNS queries. HTTP/2 provides further advice about the use of
compression ([RFC7540] Section 10.6) and padding ([RFC7540] compression ([RFC7540] Section 10.6) and padding ([RFC7540]
Section 10.7 ). DoH Servers can also add DNS padding [RFC7830] if Section 10.7 ). DoH Servers can also add DNS padding [RFC7830] if
the DoH requests it in the DNS query. the DoH client requests it in the DNS query.
The HTTPS connection provides transport security for the interaction The HTTPS connection provides transport security for the interaction
between the DoH server and client, but does not provide the response between the DoH server and client, but does not provide the response
integrity of DNS data provided by DNSSEC. DNSSEC and DoH are integrity of DNS data provided by DNSSEC. DNSSEC and DoH are
independent and fully compatible protocols, each solving different independent and fully compatible protocols, each solving different
problems. The use of one does not diminish the need nor the problems. The use of one does not diminish the need nor the
usefulness of the other. It is the choice of a client to either usefulness of the other. It is the choice of a client to either
perform full DNSSEC validation of answers or to trust the DoH server perform full DNSSEC validation of answers or to trust the DoH server
to do DNSSEC validation and inspect the AD (Authentic Data) bit in to do DNSSEC validation and inspect the AD (Authentic Data) bit in
the returned message to determine whether an answer was authentic or the returned message to determine whether an answer was authentic or
skipping to change at page 13, line 44 skipping to change at page 15, line 44
can affect that client's view of the DNS. This is no different than can affect that client's view of the DNS. This is no different than
the security implications of HTTP caching for other protocols that the security implications of HTTP caching for other protocols that
use HTTP. use HTTP.
In the absence of DNSSEC information, a DoH server can give a client In the absence of DNSSEC information, a DoH server can give a client
invalid data in response to a DNS query. Section 4 disallows the use invalid data in response to a DNS query. Section 4 disallows the use
of DoH DNS responses that do not originate from configured servers. of DoH DNS responses that do not originate from configured servers.
This prohibition does not guarantee protection against invalid data, This prohibition does not guarantee protection against invalid data,
but it does reduce the risk. but it does reduce the risk.
10. Operational Considerations 11. Operational Considerations
Local policy considerations and similar factors mean different DNS Local policy considerations and similar factors mean different DNS
servers may provide different results to the same query: for instance servers may provide different results to the same query: for instance
in split DNS configurations [RFC6950]. It logically follows that the in split DNS configurations [RFC6950]. It logically follows that the
server which is queried can influence the end result. Therefore a server which is queried can influence the end result. Therefore a
client's choice of DNS server may affect the responses it gets to its client's choice of DNS server may affect the responses it gets to its
queries. For example, in the case of DNS64 [RFC6147], the choice queries. For example, in the case of DNS64 [RFC6147], the choice
could affect whether IPv6/IPv4 translation will work at all. could affect whether IPv6/IPv4 translation will work at all.
The HTTPS channel used by this specification establishes secure two The HTTPS channel used by this specification establishes secure two
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was not able to retrieve a full answer for the query but is providing 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 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 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 example, a DoH server could use an HTTP error instead of a non-error
response that has the TC bit set. response that has the TC bit set.
Many extensions to DNS, using [RFC6891], have been defined over the Many extensions to DNS, using [RFC6891], have been defined over the
years. Extensions that are specific to the choice of transport, such years. Extensions that are specific to the choice of transport, such
as [RFC7828], are not applicable to DoH. as [RFC7828], are not applicable to DoH.
11. References 12. References
11.1. Normative References 12.1. Normative References
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/info/rfc1035>. November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 15, line 35 skipping to change at page 17, line 35
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>. <https://www.rfc-editor.org/info/rfc4648>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, (TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008, DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>. <https://www.rfc-editor.org/info/rfc5246>.
[RFC6265] Barth, A., "HTTP State Management Mechanism", RFC 6265,
DOI 10.17487/RFC6265, April 2011,
<https://www.rfc-editor.org/info/rfc6265>.
[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M., [RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
and D. Orchard, "URI Template", RFC 6570, and D. Orchard, "URI Template", RFC 6570,
DOI 10.17487/RFC6570, March 2012, 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 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014, RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>. <https://www.rfc-editor.org/info/rfc7230>.
skipping to change at page 16, line 29 skipping to change at page 18, line 29
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015, 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 [RFC7541] Peon, R. and H. Ruellan, "HPACK: Header Compression for
HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015, 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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
11.2. Informative References 12.2. Informative References
[CORS] "Cross-Origin Resource Sharing", n.d., [CORS] "Cross-Origin Resource Sharing", n.d.,
<https://fetch.spec.whatwg.org/#http-cors-protocol>. <https://fetch.spec.whatwg.org/#http-cors-protocol>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000, DOI 10.17487/RFC2818, May 2000,
<https://www.rfc-editor.org/info/rfc2818>. <https://www.rfc-editor.org/info/rfc2818>.
[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
"Transport Layer Security (TLS) Session Resumption without
Server-Side State", RFC 5077, DOI 10.17487/RFC5077,
January 2008, <https://www.rfc-editor.org/info/rfc5077>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, (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 [RFC5861] Nottingham, M., "HTTP Cache-Control Extensions for Stale
Content", RFC 5861, DOI 10.17487/RFC5861, May 2010, Content", RFC 5861, DOI 10.17487/RFC5861, May 2010,
<https://www.rfc-editor.org/info/rfc5861>. <https://www.rfc-editor.org/info/rfc5861>.
skipping to change at page 17, line 32 skipping to change at page 19, line 42
"Architectural Considerations on Application Features in "Architectural Considerations on Application Features in
the DNS", RFC 6950, DOI 10.17487/RFC6950, October 2013, 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., [RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A.,
Galperin, S., and C. Adams, "X.509 Internet Public Key Galperin, S., and C. Adams, "X.509 Internet Public Key
Infrastructure Online Certificate Status Protocol - OCSP", Infrastructure Online Certificate Status Protocol - OCSP",
RFC 6960, DOI 10.17487/RFC6960, June 2013, RFC 6960, DOI 10.17487/RFC6960, June 2013,
<https://www.rfc-editor.org/info/rfc6960>. <https://www.rfc-editor.org/info/rfc6960>.
[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
2014, <https://www.rfc-editor.org/info/rfc7258>.
[RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP
Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014,
<https://www.rfc-editor.org/info/rfc7413>.
[RFC7828] Wouters, P., Abley, J., Dickinson, S., and R. Bellis, "The [RFC7828] Wouters, P., Abley, J., Dickinson, S., and R. Bellis, "The
edns-tcp-keepalive EDNS0 Option", RFC 7828, edns-tcp-keepalive EDNS0 Option", RFC 7828,
DOI 10.17487/RFC7828, April 2016, DOI 10.17487/RFC7828, April 2016,
<https://www.rfc-editor.org/info/rfc7828>. <https://www.rfc-editor.org/info/rfc7828>.
[RFC7830] Mayrhofer, A., "The EDNS(0) Padding Option", RFC 7830, [RFC7830] Mayrhofer, A., "The EDNS(0) Padding Option", RFC 7830,
DOI 10.17487/RFC7830, May 2016, DOI 10.17487/RFC7830, May 2016,
<https://www.rfc-editor.org/info/rfc7830>. <https://www.rfc-editor.org/info/rfc7830>.
[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
 End of changes. 17 change blocks. 
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