draft-ietf-dnsop-no-response-issue-06.txt   draft-ietf-dnsop-no-response-issue-07.txt 
Network Working Group M. Andrews Network Working Group M. Andrews
Internet-Draft ISC Internet-Draft ISC
Intended status: Best Current Practice October 27, 2016 Intended status: Best Current Practice March 2, 2017
Expires: April 30, 2017 Expires: September 3, 2017
A Common Operational Problem in DNS Servers - Failure To Respond. A Common Operational Problem in DNS Servers - Failure To Respond.
draft-ietf-dnsop-no-response-issue-06 draft-ietf-dnsop-no-response-issue-07
Abstract Abstract
The DNS is a query / response protocol. Failure to respond or to The DNS is a query / response protocol. Failure to respond or to
respond correctly to queries causes both immediate operational respond correctly to queries causes both immediate operational
problems and long term problems with protocol development. problems and long term problems with protocol development.
This document identifies a number of common kinds of queries to which This document identifies a number of common kinds of queries to which
some servers either fail to respond or else respond incorrectly. some servers either fail to respond or else respond incorrectly.
This document also suggests procedures for TLD and other zone This document also suggests procedures for TLD and other zone
skipping to change at page 1, line 40 skipping to change at page 1, line 40
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 April 30, 2017. This Internet-Draft will expire on September 3, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2017 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://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
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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3.2.5. Truncated EDNS Responses . . . . . . . . . . . . . . 8 3.2.5. Truncated EDNS Responses . . . . . . . . . . . . . . 8
3.2.6. DNSSEC . . . . . . . . . . . . . . . . . . . . . . . 8 3.2.6. DNSSEC . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.7. EDNS over TCP . . . . . . . . . . . . . . . . . . . . 8 3.2.7. EDNS over TCP . . . . . . . . . . . . . . . . . . . . 8
4. Firewalls and Load Balancers . . . . . . . . . . . . . . . . 8 4. Firewalls and Load Balancers . . . . . . . . . . . . . . . . 8
5. Scrubbing Services . . . . . . . . . . . . . . . . . . . . . 9 5. Scrubbing Services . . . . . . . . . . . . . . . . . . . . . 9
6. Whole Answer Caches . . . . . . . . . . . . . . . . . . . . . 9 6. Whole Answer Caches . . . . . . . . . . . . . . . . . . . . . 9
7. Response Code Selection . . . . . . . . . . . . . . . . . . . 10 7. Response Code Selection . . . . . . . . . . . . . . . . . . . 10
8. Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8. Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Testing - Basic DNS . . . . . . . . . . . . . . . . . . . 11 8.1. Testing - Basic DNS . . . . . . . . . . . . . . . . . . . 11
8.1.1. Is The Server Configured For The Zone? . . . . . . . 11 8.1.1. Is The Server Configured For The Zone? . . . . . . . 11
8.1.2. Testing Unknown Types? . . . . . . . . . . . . . . . 11 8.1.2. Testing Unknown Types . . . . . . . . . . . . . . . . 11
8.1.3. Testing Header Bits . . . . . . . . . . . . . . . . . 12 8.1.3. Testing Header Bits . . . . . . . . . . . . . . . . . 12
8.1.4. Testing Unknown Opcodes . . . . . . . . . . . . . . . 13 8.1.4. Testing Unknown Opcodes . . . . . . . . . . . . . . . 14
8.1.5. Testing Rescursive Queries . . . . . . . . . . . . . 13 8.1.5. Testing Recursive Queries . . . . . . . . . . . . . . 15
8.1.6. Testing TCP . . . . . . . . . . . . . . . . . . . . . 14 8.1.6. Testing TCP . . . . . . . . . . . . . . . . . . . . . 15
8.2. Testing - Extended DNS . . . . . . . . . . . . . . . . . 14 8.2. Testing - Extended DNS . . . . . . . . . . . . . . . . . 16
8.2.1. Testing Minimal EDNS . . . . . . . . . . . . . . . . 14 8.2.1. Testing Minimal EDNS . . . . . . . . . . . . . . . . 16
8.2.2. Testing EDNS Version Negotiation . . . . . . . . . . 14 8.2.2. Testing EDNS Version Negotiation . . . . . . . . . . 16
8.2.3. Testing Unknown EDNS Options . . . . . . . . . . . . 15 8.2.3. Testing Unknown EDNS Options . . . . . . . . . . . . 17
8.2.4. Testing Unknown EDNS Flags . . . . . . . . . . . . . 15 8.2.4. Testing Unknown EDNS Flags . . . . . . . . . . . . . 18
8.2.5. Testing EDNS Version Negotiation With Unknown EDNS 8.2.5. Testing EDNS Version Negotiation With Unknown EDNS
Flags . . . . . . . . . . . . . . . . . . . . . . . . 16 Flags . . . . . . . . . . . . . . . . . . . . . . . . 18
8.2.6. Testing EDNS Version Negotiation With Unknown EDNS 8.2.6. Testing EDNS Version Negotiation With Unknown EDNS
Options . . . . . . . . . . . . . . . . . . . . . . . 16 Options . . . . . . . . . . . . . . . . . . . . . . . 19
8.2.7. Testing DNSSEC Queries . . . . . . . . . . . . . . . 17 8.2.7. Testing DNSSEC Queries . . . . . . . . . . . . . . . 20
8.2.8. Testing EDNS Version Negotiation With DNSSEC . . . . 17 8.2.8. Testing EDNS Version Negotiation With DNSSEC . . . . 20
8.2.9. Testing With Multiple Defined EDNS Options . . . . . 18 8.2.9. Testing With Multiple Defined EDNS Options . . . . . 21
8.3. When EDNS Is Not Supported . . . . . . . . . . . . . . . 18 8.3. When EDNS Is Not Supported . . . . . . . . . . . . . . . 21
9. Remediation . . . . . . . . . . . . . . . . . . . . . . . . . 18 9. Remediation . . . . . . . . . . . . . . . . . . . . . . . . . 22
10. Security Considerations . . . . . . . . . . . . . . . . . . . 20 10. Security Considerations . . . . . . . . . . . . . . . . . . . 23
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
12. Normative References . . . . . . . . . . . . . . . . . . . . 20 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 21 12.1. Normative References . . . . . . . . . . . . . . . . . . 23
12.2. Informative References . . . . . . . . . . . . . . . . . 24
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
The DNS [RFC1034], [RFC1035] is a query / response protocol. Failure The DNS [RFC1034], [RFC1035] is a query / response protocol. Failure
to respond to queries or to respond incorrectly causes both immediate to respond to queries or to respond incorrectly causes both immediate
operational problems and long term problems with protocol operational problems and long term problems with protocol
development. development.
Failure to respond to a query is indistinguishable from a packet loss Failure to respond to a query is indistinguishable from a packet loss
without doing a analysis of query response patterns. Additionally without doing a analysis of query response patterns. Additionally
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The tests below use dig from BIND 9.11.0. The tests below use dig from BIND 9.11.0.
8.1. Testing - Basic DNS 8.1. Testing - Basic DNS
This first set of tests cover basic DNS server behaviour and all This first set of tests cover basic DNS server behaviour and all
servers should pass these tests. servers should pass these tests.
8.1.1. Is The Server Configured For The Zone? 8.1.1. Is The Server Configured For The Zone?
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set and without
EDNS.
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response, RA may also be set [RFC1034]. We do not expect
a OPT record to be returned [RFC6891].
Verify the server is configured for the zone: Verify the server is configured for the zone:
dig +noedns +noad +norec soa $zone @$server dig +noedns +noad +norec soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: rd to NOT be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
expect: the OPT record to NOT be present expect: the OPT record to NOT be present
8.1.2. Testing Unknown Types? 8.1.2. Testing Unknown Types
Ask for the TYPE1000 record at the zone's name. This query is made
with no DNS flag bits set and without EDNS. TYPE1000 has been chosen
for this purpose as IANA is unlikely to allocate this type in the
near future and it is not in type space reserved for end user
allocation.
We don't expect any records to be returned in the answer section with
the rcode set to NOERROR and the AA and QR bits to be set in the
response, RA may also be set [RFC1034]. We do not expect a OPT
record to be returned [RFC6891].
Check that queries for an unknown type work: Check that queries for an unknown type work:
dig +noedns +noad +norec type1000 $zone @$server dig +noedns +noad +norec type1000 $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: an empty answer section. expect: an empty answer section.
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: rd to NOT be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
expect: the OPT record to NOT be present expect: the OPT record to NOT be present
That new types are to be expected is specified in Section 3.6, That new types are to be expected is specified in Section 3.6,
[RFC1035]. Servers that don't support a new type are expected to [RFC1035]. Servers that don't support a new type are expected to
reject a zone that contains a unsupported type as per Section 5.2, reject a zone that contains a unsupported type as per Section 5.2,
[RFC1035]. This means that a server that does load a zone can answer [RFC1035]. This means that a server that does load a zone can answer
questions for unknown types with NOERROR or NXDOMAIN as per questions for unknown types with NOERROR or NXDOMAIN as per
Section 4.3.2, [RFC1034]. [RFC6895] later reserved distinct ranges Section 4.3.2, [RFC1034]. [RFC6895] later reserved distinct ranges
for meta and data types which allows servers to be definitive about for meta and data types which allows servers to be definitive about
whether a query should be answerable from zone content or not. whether a query should be answerable from zone content or not.
8.1.3. Testing Header Bits 8.1.3. Testing Header Bits
8.1.3.1. Testing CD=1 Queries 8.1.3.1. Testing CD=1 Queries
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with only the CD DNS flag bit set and
all other DNS bits clear and without EDNS.
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response. We do not expect a OPT record to be returned.
If the server supports DNSSEC, CD should be set in the response
[RFC4035] otherwise CD should be clear [RFC1034].
Check that queries with CD=1 work: Check that queries with CD=1 work:
dig +noedns +noad +norec +cd soa $zone @$server dig +noedns +noad +norec +cd soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: rd to NOT be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
expect: the OPT record to NOT be present expect: the OPT record to NOT be present
CD use in queries is defined in [RFC4035]. CD use in queries is defined in [RFC4035].
8.1.3.2. Testing AD=1 Queries 8.1.3.2. Testing AD=1 Queries
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with only the AD DNS flag bit set and
all other DNS bits clear and without EDNS.
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response. We do not expect a OPT record to be returned.
If the server supports DNSSEC, AD may be set in the response
[RFC6840] otherwise AD should be clear [RFC1034].
Check that queries with AD=1 work: Check that queries with AD=1 work:
dig +noedns +norec +ad soa $zone @$server dig +noedns +norec +ad soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: ad to NOT be present expect: flag: rd to NOT be present
expect: the OPT record to NOT be present expect: the OPT record to NOT be present
AD use in queries is defined in [RFC6840]. AD use in queries is defined in [RFC6840].
8.1.3.3. Testing Reserved Bit 8.1.3.3. Testing Reserved Bit
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with only the final reserved DNS flag
bit set and all other DNS bits clear and without EDNS.
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response, RA may be set. The final reserved bit must not
be set [RFC1034]. We do not expect a OPT record to be returned
[RFC6891].
Check that queries with the last unassigned DNS header flag work and Check that queries with the last unassigned DNS header flag work and
that the flag bit is not copied to the response: that the flag bit is not copied to the response:
dig +noedns +noad +norec +zflag soa $zone @$server dig +noedns +noad +norec +zflag soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: MBZ to NOT be in the response expect: MBZ to NOT be in the response
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: rd to NOT be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
expect: the OPT record to NOT be present expect: the OPT record to NOT be present
MBZ (Must Be Zero) presence indicates the flag bit has been MBZ (Must Be Zero) presence indicates the flag bit has been
incorrectly copied. See Section 4.1.1, [RFC1035] "Z Reserved for incorrectly copied. See Section 4.1.1, [RFC1035] "Z Reserved for
future use. Must be zero in all queries and responses." future use. Must be zero in all queries and responses."
8.1.4. Testing Unknown Opcodes 8.1.4. Testing Unknown Opcodes
Construct a DNS message that consists of only a DNS header with
opcode set to 15 (currently not allocated), no DNS header bits set
and empty question, answer, authority and additional sections.
Check that new opcodes are handled: Check that new opcodes are handled:
dig +noedns +noad +opcode=15 +norec +header-only @$server dig +noedns +noad +opcode=15 +norec +header-only @$server
expect: status: NOTIMP expect: status: NOTIMP
expect: SOA record to NOT be present expect: SOA record to NOT be present
expect: flag: aa to NOT be present expect: flag: aa to NOT be present
expect: flag: rd to NOT be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
expect: the OPT record to NOT be present expect: the OPT record to NOT be present
As unknown opcodes have no definition, including packet format other As unknown opcodes have no definition, including packet format other
than there must be a DNS header present, there is only one possible than there must be a DNS header present (QR, OPCODE and RCODE are the
rcode that make sense to return to a request with a unknown opcode only header fields that need to be common across all opcodes,
and that is NOTIMP. everything else in the header can potentially be redefined), there is
only one possible rcode that make sense to return to a request with a
unknown opcode and that is NOTIMP.
8.1.5. Testing Rescursive Queries 8.1.5. Testing Recursive Queries
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with only the RD DNS flag bit set and
without EDNS.
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA, QR and RD bits to
be set in the response, RA may also be set [RFC1034]. We do not
expect a OPT record to be returned [RFC6891].
Check that recursive queries work: Check that recursive queries work:
dig +noedns +noad +rec soa $zone @$server dig +noedns +noad +rec soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: ad to NOT be present
expect: flag: rd to be present expect: flag: rd to be present
expect: flag: ad to NOT be present
expect: the OPT record to NOT be present expect: the OPT record to NOT be present
8.1.6. Testing TCP 8.1.6. Testing TCP
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set and without
EDNS. This query is to be sent using TCP.
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response, RA may also be set [RFC1034]. We do not expect
a OPT record to be returned [RFC6891].
Check that TCP queries work: Check that TCP queries work:
dig +noedns +noad +norec +tcp soa $zone @$server dig +noedns +noad +norec +tcp soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: rd to NOT be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
expect: the OPT record to NOT be present expect: the OPT record to NOT be present
The requirement that TCP be supported is defined in [RFC7766]. The requirement that TCP be supported is defined in [RFC7766].
8.2. Testing - Extended DNS 8.2. Testing - Extended DNS
The next set of test cover various aspects of EDNS behaviour. If any The next set of test cover various aspects of EDNS behaviour. If any
of these tests succeed, then all of them should succeed. There are of these tests succeed, then all of them should succeed. There are
servers that support EDNS but fail to handle plain EDNS queries servers that support EDNS but fail to handle plain EDNS queries
correctly so a plain EDNS query is not a good indicator of lack of correctly so a plain EDNS query is not a good indicator of lack of
EDNS support. EDNS support.
8.2.1. Testing Minimal EDNS 8.2.1. Testing Minimal EDNS
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set. EDNS
version 0 is used without any EDNS options or EDNS flags set.
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response, RA may also be set [RFC1034]. We expect a OPT
record to be returned. There should be no EDNS flags present in the
response. The EDNS version field should be zero and there should be
no EDNS options present [RFC6891].
Check that plain EDNS queries work: Check that plain EDNS queries work:
dig +nocookie +edns=0 +noad +norec soa $zone @$server dig +nocookie +edns=0 +noad +norec soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: a OPT record to be present in the additional section expect: a OPT record to be present in the additional section
expect: EDNS Version 0 in response expect: EDNS Version 0 in response
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
+nocookie disables sending a EDNS COOKIE option in which is on by +nocookie disables sending a EDNS COOKIE option in which is on by
default. default in BIND 9.11.0.
8.2.2. Testing EDNS Version Negotiation 8.2.2. Testing EDNS Version Negotiation
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set. EDNS
version 1 is used without any EDNS options or EDNS flags set.
We expect the SOA record for the zone to NOT be returned in the
answer section with the extended rcode set to BADVERS and the QR bit
to be set in the response, RA may also be set [RFC1034]. We expect a
OPT record to be returned. There should be no EDNS flags present in
the response. The EDNS version field should be zero as EDNS versions
other than 0 are yet to be specified and there should be no EDNS
options present [RFC6891].
Check that EDNS version 1 queries work (EDNS supported): Check that EDNS version 1 queries work (EDNS supported):
dig +nocookie +edns=1 +noednsneg +noad +norec soa $zone @$server dig +nocookie +edns=1 +noednsneg +noad +norec soa $zone @$server
expect: status: BADVERS expect: status: BADVERS
expect: the SOA record to NOT be present in the answer section expect: the SOA record to NOT be present in the answer section
expect: a OPT record to be present in the additional section expect: a OPT record to be present in the additional section
expect: EDNS Version 0 in response expect: EDNS Version 0 in response
expect: flag: aa to NOT be present expect: flag: aa to NOT be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
Only EDNS Version 0 is currently defined so the response should Only EDNS Version 0 is currently defined so the response should
always be a 0 version. This will change when EDNS version 1 is always be a 0 version. This will change when EDNS version 1 is
defined. BADVERS is the expected rcode if EDNS is supported as per defined. BADVERS is the expected rcode if EDNS is supported as per
Section 6.1.3, [RFC6891]. Section 6.1.3, [RFC6891].
8.2.3. Testing Unknown EDNS Options 8.2.3. Testing Unknown EDNS Options
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set. EDNS
version 0 is used without any EDNS flags. A EDNS option is present
with a value from the yet to be assigned range. The unassigned value
chosen is 100 and will need to be adjusted when IANA assigns this
value formally.
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response, RA may also be set [RFC1034]. We expect a OPT
record to be returned. There should be no EDNS flags present in the
response. The EDNS version field should be zero as EDNS versions
other than 0 are yet to be specified and there should be no EDNS
options present as unknown EDNS options are supposed to be ignored by
the server [RFC6891].
Check that EDNS queries with an unknown option work (EDNS supported): Check that EDNS queries with an unknown option work (EDNS supported):
dig +nocookie +edns=0 +noad +norec +ednsopt=100 soa $zone @$server dig +nocookie +edns=0 +noad +norec +ednsopt=100 soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: a OPT record to be present in the additional section expect: a OPT record to be present in the additional section
expect: OPT=100 to NOT be present expect: OPT=100 to NOT be present
expect: EDNS Version 0 in response expect: EDNS Version 0 in response
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
Unknown EDNS options are supposed to be ignored, Section 6.1.2, Unknown EDNS options are supposed to be ignored, Section 6.1.2,
[RFC6891]. [RFC6891].
8.2.4. Testing Unknown EDNS Flags 8.2.4. Testing Unknown EDNS Flags
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set. EDNS
version 0 is used without any EDNS options. A unassigned EDNS flag
bit is set (0x40 in this case).
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response, RA may also be set [RFC1034]. We expect a OPT
record to be returned. There should be no EDNS flags present in the
response as unknown EDNS flags are supposed to be ignored. The EDNS
version field should be zero and there should be no EDNS options
present [RFC6891].
Check that EDNS queries with unknown flags work (EDNS supported): Check that EDNS queries with unknown flags work (EDNS supported):
dig +nocookie +edns=0 +noad +norec +ednsflags=0x40 soa $zone @$server dig +nocookie +edns=0 +noad +norec +ednsflags=0x40 soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: a OPT record to be present in the additional section expect: a OPT record to be present in the additional section
expect: MBZ not to be present expect: MBZ not to be present
expect: EDNS Version 0 in response expect: EDNS Version 0 in response
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
MBZ (Must Be Zero) presence indicates the flag bit has been MBZ (Must Be Zero) presence indicates the flag bit has been
incorrectly copied as per Section 6.1.4, [RFC6891]. incorrectly copied as per Section 6.1.4, [RFC6891].
8.2.5. Testing EDNS Version Negotiation With Unknown EDNS Flags 8.2.5. Testing EDNS Version Negotiation With Unknown EDNS Flags
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set. EDNS
version 1 is used without any EDNS options. A unassigned EDNS flag
bit is set (0x40 in this case).
We expect the SOA record for the zone to NOT be returned in the
answer section with the extended rcode set to BADVERS and the QR bit
to be set in the response, RA may also be set [RFC1034]. We expect a
OPT record to be returned. There should be no EDNS flags present in
the response as unknown EDNS flags are supposed to be ignored. The
EDNS version field should be zero as EDNS versions other than 0 are
yet to be specified and there should be no EDNS options present
[RFC6891].
Check that EDNS version 1 queries with unknown flags work (EDNS Check that EDNS version 1 queries with unknown flags work (EDNS
supported): supported):
dig +nocookie +edns=1 +noednsneg +noad +norec +ednsflags=0x40 soa \ dig +nocookie +edns=1 +noednsneg +noad +norec +ednsflags=0x40 soa \
$zone @$server $zone @$server
expect: status: BADVERS expect: status: BADVERS
expect: SOA record to NOT be present expect: SOA record to NOT be present
expect: a OPT record to be present in the additional section expect: a OPT record to be present in the additional section
expect: MBZ not to be present expect: MBZ not to be present
expect: EDNS Version 0 in response expect: EDNS Version 0 in response
expect: flag: aa to NOT be present expect: flag: aa to NOT be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
+noednsneg disables EDNS version negotiation in DiG; MBZ (Must Be +noednsneg disables EDNS version negotiation in DiG; MBZ (Must Be
Zero) presence indicates the flag bit has been incorrectly copied. Zero) presence indicates the flag bit has been incorrectly copied.
8.2.6. Testing EDNS Version Negotiation With Unknown EDNS Options 8.2.6. Testing EDNS Version Negotiation With Unknown EDNS Options
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set. EDNS
version 1 is used. A unknown EDNS option is present (option code 100
has been chosen).
We expect the SOA record for the zone to NOT be returned in the
answer section with the extended rcode set to BADVERS and the QR bit
to be set in the response, RA may also be set [RFC1034]. We expect a
OPT record to be returned. There should be no EDNS flags present in
the response. The EDNS version field should be zero as EDNS versions
other than 0 are yet to be specified and there should be no EDNS
options present [RFC6891].
Check that EDNS version 1 queries with unknown options work (EDNS Check that EDNS version 1 queries with unknown options work (EDNS
supported): supported):
dig +nocookie +edns=1 +noednsneg +noad +norec +ednsopt=100 soa \ dig +nocookie +edns=1 +noednsneg +noad +norec +ednsopt=100 soa \
$zone @$server $zone @$server
expect: status: BADVERS expect: status: BADVERS
expect: SOA record to NOT be present expect: SOA record to NOT be present
expect: a OPT record to be present in the additional section expect: a OPT record to be present in the additional section
expect: OPT=100 to NOT be present expect: OPT=100 to NOT be present
expect: EDNS Version 0 in response expect: EDNS Version 0 in response
expect: flag: aa to be present expect: flag: aa to be present
expect: flag: ad to NOT be present expect: flag: ad to NOT be present
+noednsneg disables EDNS version negotiation in DiG. +noednsneg disables EDNS version negotiation in DiG.
8.2.7. Testing DNSSEC Queries 8.2.7. Testing DNSSEC Queries
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set. EDNS
version 0 is used without any EDNS options. The only EDNS flag set
is DO.
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response, AD may be set in the response if the server
supports DNSSEC otherwise it should be clear. RA may also be set
[RFC1034]. We expect a OPT record to be returned. There should be
no EDNS flags other than DO present in the response which should be
present if the server supports DNSSEC. The EDNS version field should
be zero and there should be no EDNS options present [RFC6891].
Check that a DNSSEC queries work (EDNS supported): Check that a DNSSEC queries work (EDNS supported):
dig +nocookie +edns=0 +noad +norec +dnssec soa $zone @$server dig +nocookie +edns=0 +noad +norec +dnssec soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: a OPT record to be present in the additional section expect: a OPT record to be present in the additional section
expect: DO=1 to be present if a RRSIG is in the response expect: DO=1 to be present if a RRSIG is in the response
expect: EDNS Version 0 in response expect: EDNS Version 0 in response
expect: flag: aa to be present expect: flag: aa to be present
DO=1 should be present if RRSIGs are returned as they indicate that DO=1 should be present if RRSIGs are returned as they indicate that
the server supports DNSSEC. Servers that support DNSSEC are supposed the server supports DNSSEC. Servers that support DNSSEC are supposed
to copy the DO bit from the request to the response as per [RFC3225]. to copy the DO bit from the request to the response as per [RFC3225].
8.2.8. Testing EDNS Version Negotiation With DNSSEC 8.2.8. Testing EDNS Version Negotiation With DNSSEC
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set. EDNS
version 1 is used without any EDNS options. The only EDNS flag set
is DO.
We expect the SOA record for the zone to NOT be returned in the
answer section with the rcode set to BADVERS and the only the QR bit
and possibly the RA bit to be set [RFC1034]. We expect a OPT record
to be returned. There should be no EDNS flags other than DO present
in the response which should be present if the server supports
DNSSEC. The EDNS version field should be zero and there should be no
EDNS options present [RFC6891].
Check that EDNS version 1 DNSSEC queries work (EDNS supported): Check that EDNS version 1 DNSSEC queries work (EDNS supported):
dig +nocookie +edns=1 +noednsneg +noad +norec +dnssec soa \ dig +nocookie +edns=1 +noednsneg +noad +norec +dnssec soa \
$zone @$server $zone @$server
expect: status: BADVERS expect: status: BADVERS
expect: SOA record to NOT be present expect: SOA record to NOT be present
expect: a OPT record to be present in the additional section expect: a OPT record to be present in the additional section
expect: DO=1 to be present if the EDNS version 0 DNSSEC query test expect: DO=1 to be present if the EDNS version 0 DNSSEC query test
returned DO=1 returned DO=1
expect: EDNS Version 0 in response expect: EDNS Version 0 in response
expect: flag: aa to NOT be present expect: flag: aa to NOT be present
+noednsneg disables EDNS version negotiation in DiG. +noednsneg disables EDNS version negotiation in DiG.
8.2.9. Testing With Multiple Defined EDNS Options 8.2.9. Testing With Multiple Defined EDNS Options
Ask for the SOA record of the zone the server is nominally configured
to serve. This query is made with no DNS flag bits set. EDNS
version 0 is used. A number of defined EDNS options are present
(NSID [RFC5001], DNS COOKIE [RFC7873], EDNS Client Subnet [RFC7871]
and EDNS Expire [RFC7314]).
We expect the SOA record for the zone to be returned in the answer
section with the rcode set to NOERROR and the AA and QR bits to be
set in the response, RA may also be set [RFC1034]. We expect a OPT
record to be returned. There should be no EDNS flags present in the
response. The EDNS version field should be zero. Any of the
requested EDNS options supported by the server and permitted server
configuration may be returned [RFC6891].
Check that EDNS queries with multiple defined EDNS options work: Check that EDNS queries with multiple defined EDNS options work:
dig +edns=0 +noad +norec +cookie +nsid +expire +subnet=0.0.0.0/0 \ dig +edns=0 +noad +norec +cookie +nsid +expire +subnet=0.0.0.0/0 \
soa $zone @$server soa $zone @$server
expect: status: NOERROR expect: status: NOERROR
expect: the SOA record to be present in the answer section expect: the SOA record to be present in the answer section
expect: a OPT record to be present in the additional section expect: a OPT record to be present in the additional section
expect: EDNS Version 0 in response expect: EDNS Version 0 in response
expect: flag: aa to be present expect: flag: aa to be present
skipping to change at page 20, line 27 skipping to change at page 23, line 40
settings. settings.
When removing delegations for non-compliant servers there can be a When removing delegations for non-compliant servers there can be a
knock on effect on other zones that require these zones to be knock on effect on other zones that require these zones to be
operational for the nameservers addresses to be resolved. operational for the nameservers addresses to be resolved.
11. IANA Considerations 11. IANA Considerations
There are no actions for IANA. There are no actions for IANA.
12. Normative References 12. References
12.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<http://www.rfc-editor.org/info/rfc1034>. <http://www.rfc-editor.org/info/rfc1034>.
[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, <http://www.rfc-editor.org/info/rfc1035>. November 1987, <http://www.rfc-editor.org/info/rfc1035>.
[RFC3225] Conrad, D., "Indicating Resolver Support of DNSSEC", [RFC3225] Conrad, D., "Indicating Resolver Support of DNSSEC",
skipping to change at page 21, line 19 skipping to change at page 24, line 33
[RFC6895] Eastlake 3rd, D., "Domain Name System (DNS) IANA [RFC6895] Eastlake 3rd, D., "Domain Name System (DNS) IANA
Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895, Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895,
April 2013, <http://www.rfc-editor.org/info/rfc6895>. April 2013, <http://www.rfc-editor.org/info/rfc6895>.
[RFC7766] Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and [RFC7766] Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and
D. Wessels, "DNS Transport over TCP - Implementation D. Wessels, "DNS Transport over TCP - Implementation
Requirements", RFC 7766, DOI 10.17487/RFC7766, March 2016, Requirements", RFC 7766, DOI 10.17487/RFC7766, March 2016,
<http://www.rfc-editor.org/info/rfc7766>. <http://www.rfc-editor.org/info/rfc7766>.
12.2. Informative References
[RFC5001] Austein, R., "DNS Name Server Identifier (NSID) Option",
RFC 5001, DOI 10.17487/RFC5001, August 2007,
<http://www.rfc-editor.org/info/rfc5001>.
[RFC7314] Andrews, M., "Extension Mechanisms for DNS (EDNS) EXPIRE
Option", RFC 7314, DOI 10.17487/RFC7314, July 2014,
<http://www.rfc-editor.org/info/rfc7314>.
[RFC7871] Contavalli, C., van der Gaast, W., Lawrence, D., and W.
Kumari, "Client Subnet in DNS Queries", RFC 7871,
DOI 10.17487/RFC7871, May 2016,
<http://www.rfc-editor.org/info/rfc7871>.
[RFC7873] Eastlake 3rd, D. and M. Andrews, "Domain Name System (DNS)
Cookies", RFC 7873, DOI 10.17487/RFC7873, May 2016,
<http://www.rfc-editor.org/info/rfc7873>.
Author's Address Author's Address
M. Andrews M. Andrews
Internet Systems Consortium Internet Systems Consortium
950 Charter Street 950 Charter Street
Redwood City, CA 94063 Redwood City, CA 94063
US US
Email: marka@isc.org Email: marka@isc.org
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