Network Working Group S. Bortzmeyer
Internet-Draft AFNIC
Obsoletes: 7816 (if approved) R. Dolmans
Intended status: Standards Track NLnet Labs
Expires: September 7, 2020 P. Hoffman
ICANN
March 6, 2020
DNS Query Name Minimisation to Improve Privacy
draft-ietf-dnsop-rfc7816bis-03
Abstract
This document describes techniques called "QNAME minimisation" to
improve DNS privacy, where the DNS resolver no longer always sends
the full original QNAME to the upstream name server. This document
obsoletes RFC 7816.
This document is part of the IETF DNSOP (DNS Operations) Working
Group. The source of the document, as well as a list of open issues,
is at <https://framagit.org/bortzmeyer/rfc7816-bis>
NOTE FOR THE DNSOP WORKING GROUP: There is still much work to be done
in this draft. Future versions of this draft will contain
descriptions of different minimisation implementation choices that
have been made since the RFC 7816 first came out, as well as
deployment experience.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 7, 2020.
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Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Introduction and Background . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Description of QNAME Minimisation . . . . . . . . . . . . . . 3
2.1. Algorithm to Perform Aggressive Method QNAME Minimisation 5
3. QNAME Minimisation Examples . . . . . . . . . . . . . . . . . 5
4. Limit number of queries . . . . . . . . . . . . . . . . . . . 6
5. Operational Considerations . . . . . . . . . . . . . . . . . 7
6. Performance Considerations . . . . . . . . . . . . . . . . . 9
7. Alternative Methods for QNAME Minimisation . . . . . . . . . 10
8. Results of the Experimentation . . . . . . . . . . . . . . . 10
9. Security Considerations . . . . . . . . . . . . . . . . . . . 10
10. Implementation Status . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . 13
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 14
Changes from RFC 7816 . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction and Background
The problem statement for this document and its predecessor [RFC7816]
is described in [I-D.bortzmeyer-dprive-rfc7626-bis]. The terminology
("QNAME", "resolver", etc.) is defined in
[I-D.ietf-dnsop-terminology-bis]. This specific solution is not
intended to fully solve the DNS privacy problem; instead, it should
be viewed as one tool amongst many.
QNAME minimisation follows the principle explained in Section 6.1 of
[RFC6973]: the less data you send out, the fewer privacy problems
you have.
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Before QNAME minimisation, when a resolver received the query "What
is the AAAA record for www.example.com?", it sent to the root
(assuming a resolver whose cache is empty) the very same question.
Sending the full QNAME to the authoritative name server was a
tradition, not a protocol requirement. In a conversation with the
author in January 2015, Paul Mockapetris explained that this
tradition comes from a desire to optimise the number of requests,
when the same name server is authoritative for many zones in a given
name (something that was more common in the old days, where the same
name servers served .com and the root) or when the same name server
is both recursive and authoritative (something that is strongly
discouraged now). Whatever the merits of this choice at this time,
the DNS is quite different now.
QNAME minimisation is compatible with the current DNS system and
therefore can easily be deployed. Because it is only a change to the
way that the resolver operates, it does not change the protocol. The
behaviour suggested here (minimising the amount of data sent in
QNAMEs from the resolver) is allowed by Section 5.3.3 of [RFC1034] or
Section 7.2 of [RFC1035].
1.1. Terminology
A "cold" cache is one that is empty, having literally no entries in
it. A "warm" cache is one that has some entries in it.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Description of QNAME Minimisation
The idea behind QNAME minimisation is to minimise the amount of
privacy sensitive data sent from the DNS resolver to the
authoritative name server. This section describes the RECOMMENDED
way to do QNAME minimisation -- the way that maximises privacy
benefits. That algorithm is summarized in Section 2.1.
When a resolver is not able to answer a query from cache it has to
send a query to an authoritative nameserver. Traditionally these
queries would contain the full QNAME and the original QTYPE as
received in the client query. The full QNAME and original QTYPE are
only needed at the nameserver that is authoritative for the record
requested by the client. All other nameservers queried while
resolving the query only need to receive enough of the QNAME to be
able to answer with a delegation. The QTYPE in these queries is not
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relevant, as the nameserver is not authoritative to answer with the
records the client is looking for. Sending the full QNAME and
original QTYPE to these nameservers therefore exposes more privacy
sensitive data than necessary to resolve the client's request. A
resolver that implements QNAME minimisation changes the QNAME and
QTYPE in queries to authoritative nameserver that are not known to be
responsible for the original QNAME. These request are done with:
o a QTYPE selected by the resolver to hide the original QTYPE
o the QNAME that is the original QNAME, stripped to just one label
more than the longest matching domain name for which the
nameserver is known to be authoritative
This method is called the "aggressive method" in this document
because the resolver won't expose the original QTYPE to nameservers
that are not known to be responsible for the desired name. This
method is the safest from a privacy point of view, and is thus the
RECOMMENDED method for this document. Other methods are described in
Section 7.
The QTYPE to use while minimising queries can be any possible data
TYPE RRTYPE (rfc6895 #3.1) for which the authority always lies below
the zone cut (i.e. not DS, NSEC, NSEC3, OPT, TSIG, TKEY, ANY, MAILA,
MAILB, AXFR, and IXFR), as long as there is no relation between the
incoming QTYPE and the selection of the QTYPE to use while
minimising. A good candidate is to always use the A QTYPE as this is
the least likely to give issues at DNS software and middleboxes that
do not properly support all QTYPEs. The QTYPE=A queries will also
blend into traffic from non-minimising resolvers, making it in some
cases harder to observe that the resolving has QNAME minimisation
enabled.
The minimising resolver works perfectly when it knows the zone cut
(zone cuts are described in Section 6 of [RFC2181]). But zone cuts
do not necessarily exist at every label boundary. In the name
www.foo.bar.example, it is possible that there is a zone cut between
"foo" and "bar" but not between "bar" and "example". So, assuming
that the resolver already knows the name servers of example, when it
receives the query "What is the AAAA record of www.foo.bar.example?",
it does not always know where the zone cut will be. To find the
zone cut, it will query the example name servers for a record for
bar.example. It will get a non-referral answer, it has to query the
example name servers again with one more label, and so on.
(Section 2.1 describes this algorithm in deeper detail.)
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2.1. Algorithm to Perform Aggressive Method QNAME Minimisation
This algorithm performs name resolution with aggressive method QNAME
minimisation in the presence of zone cuts that are not yet known.
Although a validating resolver already has the logic to find the
zone cuts, implementers of other resolvers may want to use this
algorithm to locate the zone cuts.
(0) If the query can be answered from the cache, do so; otherwise,
iterate as follows:
(1) Get the closest delegation point that can be used for QNAME from
the cache. This is the NS RRset with the owner matching the most
labels with the QNAME. The QNAME will be equal to or a subdomain
of this NS RRset. Call this ANCESTOR.
(2) Initialise CHILD to the same as ANCESTOR.
(3) If CHILD is the same as the QNAME, resolve the original query
using ANCESTOR's name servers, and finish.
(4) Otherwise, add a label from the QNAME to the start of CHILD.
(5) Look for a negative cache entry for the NS RRset at CHILD. If
this entry is for an NXDOMAIN and the resolver has support for
RFC8020 the NXDOMAIN can be used in response to the original
query, and stop. If the entry is for a NOERROR/NODATA answer go
back to step 3
(6) Query for CHILD with the minimised QTYPE using ANCESTOR's
name servers. The response can be:
(6a) A referral. Cache the NS RRset from the authority section,
and go back to step 1.
(6b) A NOERROR answer. Cache this answer, and go back to step 3.
(6c) An NXDOMAIN answer. Return an NXDOMAIN answer in response
to the original query, and stop.
3. QNAME Minimisation Examples
For example, a resolver receives a request to resolve
foo.bar.baz.example. Assume that the resolver already knows that
ns1.nic.example is authoritative for .example, and that the resolver
does not know a more specific authoritative name server. It will
send the query QTYPE=NS, QNAME=baz.example to ns1.nic.example.
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Here are more detailed examples of queries with the aggressive method
of QNAME minimisation:
Cold cache, traditional resolution algorithm without QNAME
minimisation, request for A record of a.b.example.org:
QTYPE QNAME TARGET NOTE
A a.b.example.org root nameserver
A a.b.example.org org nameserver
A a.b.example.org example.org nameserver
Cold cache, aggressive QNAME minimisation method, request for A
record of a.b.example.org, using NS QTYPE to hide the original QTYPE:
QTYPE QNAME TARGET NOTE
NS org root nameserver
NS example.org org nameserver
NS b.example.org example.org nameserver
NS a.b.example.org example.org nameserver "a" may be delegated
A a.b.example.org example.org nameserver
Warm cache with only org delegation known, (example.org's NS RRset is
not known), aggressive QNAME minimisation method, request for A
record of a.b.example.org, using NS QTYPE to hide the original QTYPE:
QTYPE QNAME TARGET NOTE
NS example.org org nameserver
NS b.example.org example.org nameserver
NS a.b.example.org example.org nameserver "a" may be delegated
A a.b.example.org example.org nameserver
4. Limit number of queries
When using QNAME minimisation the number of labels in the received
QNAME can influence the number of queries sent from the resolver.
This opens an attack vector and can decrease performance. Resolvers
supporting QNAME minimisation should implement a mechanism to limit
the number of outgoing queries per user request.
Take for example an incoming QNAME with many labels, like
www.host.group.department.example.com, where
host.group.department.example.com is hosted on example.com's
name servers). Assume a resolver that knows only the name servers of
example.com. Without QNAME minimisation, it would send these
example.com name servers a query for
www.host.group.department.example.com and immediately get a specific
referral or an answer, without the need for more queries to probe for
the zone cut. For such a name, a cold resolver with QNAME
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minimisation will, depending on how QNAME minimisation is
implemented, send more queries, one per label. Once the cache is
warm, there will be no difference with a traditional resolver.
Actual testing is described in [Huque-QNAME-Min]. Such deep domains
are especially common under ip6.arpa.
This behaviour can be exploited by sending queries with a large
number of labels in the QNAME that will be answered using a wildcard
record. Take for example a record for *.example.com, hosted on
example.com's name servers. An incoming query containing a QNAME
with more than 100 labels, ending in example.com, will result in a
query per label. By using random labels the attacker can bypass the
caching and always require the resolver to send many queries
upstream. Note that RFC8198 can limit this attack in some cases.
One mechanism to reduce this attack vector is by sending more than
one label per iteration for QNAMEs with a large number of labels. To
do this a maximum number of QNAME minimisation iterations has to be
selected (MAX_MINIMISE_COUNT), a good value is 10. Optionally a
value for the number of queries that should only have one label
appended can be selected (MINIMISE_ONE_LAB), a good value is 4. The
assumption here is that the number of labels on delegations higher in
the hierarchy are rather small, therefore not exposing too may labels
early on has the most privacy benefit.
When a resolver needs to send out a query if will look for the
closest known delegation point in its cache. The number of QNAME
minimisation iterations is the difference between this closest
nameserver and the incoming QNAME. The first MINIMISE_ONE_LAB
iterations will be handles as described in Section 2. The number of
labels that are not exposed yet now need to be divided over the
iterations that are left (MAX_MINIMISE_COUNT - MINIMISE_ONE_LAB).
The remainder of the division should be added to the last iterations.
For example, when resolving a QNAME with 18 labels, the number of
labels added per iteration are: 1,1,1,1,2,2,2,2,3,3.
5. Operational Considerations
TODO may be remove the whole section now that it is no longer
experimental?
QNAME minimisation is legal, since the original DNS RFCs do not
mandate sending the full QNAME. So, in theory, it should work
without any problems. However, in practice, some problems may occur
(see [Huque-QNAME-Min] for an analysis and [Huque-QNAME-Discuss] for
an interesting discussion on this topic).
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Note that the aggressive method described in this document prevents
authoritative servers other than the server for a full name from
seeing information about the relative use of the various QTYPEs.
That information may be interesting for researchers (for instance, if
they try to follow IPv6 deployment by counting the percentage of AAAA
vs. A queries).
Some broken name servers do not react properly to QTYPE=NS requests.
For instance, some authoritative name servers embedded in load
balancers reply properly to A queries but send REFUSED to NS queries.
This behaviour is a protocol violation, and there is no need to stop
improving the DNS because of such behaviour. However, QNAME
minimisation may still work with such domains, since they are only
leaf domains (no need to send them NS requests). Such a setup breaks
more than just QNAME minimisation. It breaks negative answers, since
the servers don't return the correct SOA, and it also breaks anything
dependent upon NS and SOA records existing at the top of the zone.
Another way to deal with such incorrect name servers would be to try
with QTYPE=A requests (A being chosen because it is the most common
and hence a QTYPE that will always be accepted, while a QTYPE NS may
ruffle the feathers of some middleboxes). Instead of querying
name servers with a query "NS example.com", a resolver could use
"A _.example.com" and see if it gets a referral. TODO this is what
Unbound does
A problem can also appear when a name server does not react properly
to ENTs (Empty Non-Terminals). If ent.example.com has no resource
records but foobar.ent.example.com does, then ent.example.com is an
ENT. Whatever the QTYPE, a query for ent.example.com must return
NODATA (NOERROR / ANSWER: 0). However, some name servers incorrectly
return NXDOMAIN for ENTs. If a resolver queries only
foobar.ent.example.com, everything will be OK, but if it implements
QNAME minimisation, it may query ent.example.com and get an NXDOMAIN.
See also Section 3 of [DNS-Res-Improve] for the other bad
consequences of this bad behaviour.
A possible solution, currently implemented in Knot or Unbound, is to
retry with the full query when you receive an NXDOMAIN. It works,
but it is not ideal for privacy.
Other practices that do not conform to the DNS protocol standards may
pose a problem: there is a common DNS trick used by some web hosters
that also do DNS hosting that exploits the fact that the DNS protocol
(pre-DNSSEC) allows certain serious misconfigurations, such as parent
and child zones disagreeing on the location of a zone cut.
Basically, they have a single zone with wildcards for each TLD, like:
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*.example. 60 IN A 192.0.2.6
(They could just wildcard all of "*.", which would be sufficient. It
is impossible to tell why they don't do it.)
This lets them have many web-hosting customers without having to
configure thousands of individual zones on their name servers. They
just tell the prospective customer to point their NS records at the
hoster's name servers, and the web hoster doesn't have to provision
anything in order to make the customer's domain resolve. NS queries
to the hoster will therefore not give the right result, which may
endanger QNAME minimisation (it will be a problem for DNSSEC, too).
TODO report by Akamai about why they return erroneous responses
https://mailarchive.ietf.org/arch/msg/dnsop/
XIX16DCe2ln3ZnZai723v32ZIjE
TODO what to do if the resolver forwards? Unbound disables QNAME
minimisation in that case, since the forwarder will see everything,
anyway. What should a minimising resolver do when forwading the
request to a forwarder, not to an authoritative name server? Send
the full qname? Minimises? (But how since the resolver does not
know the zone cut?)
The administrators of the forwarders, and of the authoritative
name servers, will get less data, which will reduce the utility of
the statistics they can produce (such as the percentage of the
various QTYPEs).
DNS administrators are reminded that the data on DNS requests that
they store may have legal consequences, depending on your
jurisdiction (check with your local lawyer).
6. Performance Considerations
The main goal of QNAME minimisation is to improve privacy by sending
less data. However, it may have other advantages. For instance, if
a resolver sends a root name server queries for A.example followed by
B.example followed by C.example, the result will be three NXDOMAINs,
since .example does not exist in the root zone. When using QNAME
minimisation, the resolver would send only one question (for .example
itself) to which they could answer NXDOMAIN, thus opening up a
negative caching opportunity in which the full resolver could know a
priori that neither B.example nor C.example could exist. Thus, in
this common case, the total number of upstream queries under QNAME
minimisation could be counterintuitively less than the number of
queries under the traditional iteration (as described in the DNS
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standard). TODO mention [RFC8020]? And [RFC8198], the latter
depending on DNSSEC?
QNAME minimisation may also improve lookup performance for TLD
operators. For a TLD that is delegation-only, a two-label QNAME
query may be optimal for finding the delegation owner name, depending
on the way domain matching is implemented.
QNAME minimisation can increase the number of queries based on the
incoming QNAME. This is described in Section 4.
7. Alternative Methods for QNAME Minimisation
One useful optimisation may be, in the spirit of the HAMMER idea
[HAMMER], The resolver can probe in advance for the introduction of
zone cuts where none previously existed to confirm their continued
absence or to discover them.
To reduce the number of queries (an issue described in Section 6), a
resolver could always use full name queries when the cache is cold
and then to move to the aggressive method of QNAME minimisation when
the cache is warm. (Precisely defining what is "warm" or "cold" is
left to the implementer). This will decrease the privacy for initial
queries but will guarantee no degradation of performance.
Another possible algorithm, not fully studied at this time, could be
to "piggyback" on the traditional resolution code. At startup, it
sends traditional full QNAMEs and learns the zone cuts from the
referrals received, then switches to NS queries asking only for the
minimum domain name. This leaks more data but could require fewer
changes in the existing resolver codebase.
8. Results of the Experimentation
TODO various experiences from actual deployments, problems heard.
TODO the Knot bug #339 https://gitlab.labs.nic.cz/knot/knot-resolver/
issues/339? TODO Problems with AWS https://forums.aws.amazon.com/
thread.jspa?threadID=269116?
9. Security Considerations
QNAME minimisation's benefits are clear in the case where you want to
decrease exposure to the authoritative name server. But minimising
the amount of data sent also, in part, addresses the case of a wire
sniffer as well as the case of privacy invasion by the servers.
(Encryption is of course a better defense against wire sniffers, but,
unlike QNAME minimisation, it changes the protocol and cannot be
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deployed unilaterally. Also, the effect of QNAME minimisation on
wire sniffers depends on whether the sniffer is on the DNS path.)
QNAME minimisation offers zero protection against the recursive
resolver, which still sees the full request coming from the stub
resolver.
All the alternatives mentioned in Section 7 decrease privacy in the
hope of improving performance. They must not be used if you want
maximum privacy.
10. Implementation Status
\[\[ Note to RFC Editor: Remove this entire section, and the
reference to RFC 7942, before publication. \]\]
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
Unbound has had a QNAME minimisation feature since version 1.5.7,
December 2015, (see [Dolmans-Unbound]) and it has had QNAME
minimisation turned default since version 1.7.2, June 2018. It has
two modes set by the "qname-minimisation-strict" configuration
option. In strict mode (option set to "yes"), there is no workaround
for broken authoritative name servers. In lax mode, Unbound retries
when there is a NXDOMAIN response from the minimized query. Since
November 2016, Unbound uses only queries for the A RRtype and not the
NS RRtype.
Knot Resolver has had a QNAME minimisation feature since version
1.0.0, May 2016, and it is activated by default.
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BIND has had a QNAME minimisation feature since unstable development
version 9.13.2, July 2018. It currently has several modes, with or
without workarounds for broken authoritative name servers.
The Cloudflare's public resolver at IP address 1.1.1.1 has QNAME
minimisation. (It currently uses Knot.)
Testing with one thousand RIPE Atlas probes [atlas-qname-min], one
can see that QNAME minimisation is now common:
% blaeu-resolve --requested 1000 --type TXT qnamemintest.internet.nl
["no - qname minimisation is not enabled on your resolver :("] : 888 occurrences
["hooray - qname minimisation is enabled on your resolver :)!"] : 105 occurrences
[ERROR: SERVFAIL] : 3 occurrences
Test #16113243 done at 2018-09-14T13:01:47Z
10 % of the probes have a resolver with QNAME minimisation (it is not
possible to infer the percentage of users having QNAME minimisation).
11. References
11.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[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>.
[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>.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973,
DOI 10.17487/RFC6973, July 2013,
<https://www.rfc-editor.org/info/rfc6973>.
[RFC7816] Bortzmeyer, S., "DNS Query Name Minimisation to Improve
Privacy", RFC 7816, DOI 10.17487/RFC7816, March 2016,
<https://www.rfc-editor.org/info/rfc7816>.
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[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>.
11.2. Informative References
[atlas-qname-min]
Bortzmeyer, S., "DNS resolution of
qnamemintest.internet.nl/TXT on RIPE Atlas probes",
September 2018,
<https://atlas.ripe.net/measurements/16113243/>.
[DNS-Res-Improve]
Vixie, P., Joffe, R., and F. Neves, "Improvements to DNS
Resolvers for Resiliency, Robustness, and Responsiveness",
Work in Progress, draft-vixie-dnsext-resimprove-00, June
2010.
[Dolmans-Unbound]
Dolmans, R., "Unbound QNAME minimisation @ DNS-OARC",
March 2016, <https://indico.dns-
oarc.net/event/22/contributions/332/attachments/310/542/
unbound_qnamemin_oarc24.pdf>.
[HAMMER] Kumari, W., Arends, R., Woolf, S., and D. Migault, "Highly
Automated Method for Maintaining Expiring Records", Work
in Progress, draft-wkumari-dnsop-hammer-01, July 2014.
[Huque-QNAME-Discuss]
Huque, S., "Qname Minimization @ DNS-OARC", May 2015,
<https://www.huque.com/2015/05/16/qname-min.html>.
[Huque-QNAME-Min]
Huque, S., "Query name minimization and authoritative
server behavior", May 2015,
<https://indico.dns-oarc.net/event/21/contribution/9>.
[I-D.bortzmeyer-dprive-rfc7626-bis]
Bortzmeyer, S. and S. Dickinson, "DNS Privacy
Considerations", draft-bortzmeyer-dprive-rfc7626-bis-02
(work in progress), January 2019.
[I-D.ietf-dnsop-terminology-bis]
Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", draft-ietf-dnsop-terminology-bis-14 (work in
progress), September 2018.
Bortzmeyer, et al. Expires September 7, 2020 [Page 13]
Internet-Draft QNAME Minimisation March 2020
[RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS
Specification", RFC 2181, DOI 10.17487/RFC2181, July 1997,
<https://www.rfc-editor.org/info/rfc2181>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[RFC8020] Bortzmeyer, S. and S. Huque, "NXDOMAIN: There Really Is
Nothing Underneath", RFC 8020, DOI 10.17487/RFC8020,
November 2016, <https://www.rfc-editor.org/info/rfc8020>.
[RFC8198] Fujiwara, K., Kato, A., and W. Kumari, "Aggressive Use of
DNSSEC-Validated Cache", RFC 8198, DOI 10.17487/RFC8198,
July 2017, <https://www.rfc-editor.org/info/rfc8198>.
Acknowledgments
TODO (refer to 7816)
Changes from RFC 7816
o Made changes to deal with errata #4644
o Changed status to be on standards track
o Major reorganization
Authors' Addresses
Stephane Bortzmeyer
AFNIC
1, rue Stephenson
Montigny-le-Bretonneux 78180
France
Phone: +33 1 39 30 83 46
Email: bortzmeyer+ietf@nic.fr
URI: https://www.afnic.fr/
Ralph Dolmans
NLnet Labs
Email: ralph@nlnetlabs.nl
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Paul Hoffman
ICANN
Email: paul.hoffman@icann.org
Bortzmeyer, et al. Expires September 7, 2020 [Page 15]
