7 Network Working Group M. Andrews
8 Request for Comments: 4431 Internet Systems Consortium
9 Category: Informational S. Weiler
14 The DNSSEC Lookaside Validation (DLV) DNS Resource Record
18 This memo provides information for the Internet community. It does
19 not specify an Internet standard of any kind. Distribution of this
24 Copyright (C) The Internet Society (2006).
28 This document defines a new DNS resource record, called the DNSSEC
29 Lookaside Validation (DLV) RR, for publishing DNSSEC trust anchors
30 outside of the DNS delegation chain.
34 DNSSEC [1] [2] [3] authenticates DNS data by building public-key
35 signature chains along the DNS delegation chain from a trust anchor,
36 ideally a trust anchor for the DNS root.
38 This document defines a new resource record for publishing such trust
39 anchors outside of the DNS's normal delegation chain. Use of these
40 records by DNSSEC validators is outside the scope of this document,
41 but it is expected that these records will help resolvers validate
42 DNSSEC-signed data from zones whose ancestors either aren't signed or
43 refuse to publish delegation signer (DS) records for their children.
45 2. DLV Resource Record
47 The DLV resource record has exactly the same wire and presentation
48 formats as the DS resource record, defined in RFC 4034, Section 5.
49 It uses the same IANA-assigned values in the algorithm and digest
50 type fields as the DS record. (Those IANA registries are known as
51 the "DNS Security Algorithm Numbers" and "DS RR Type Algorithm
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60 RFC 4431 DLV Resource Record February 2006
63 The DLV record is a normal DNS record type without any special
64 processing requirements. In particular, the DLV record does not
65 inherit any of the special processing or handling requirements of the
66 DS record type (described in Section 3.1.4.1 of RFC 4035). Unlike
67 the DS record, the DLV record may not appear on the parent's side of
68 a zone cut. A DLV record may, however, appear at the apex of a zone.
70 3. Security Considerations
72 For authoritative servers and resolvers that do not attempt to use
73 DLV RRs as part of DNSSEC validation, there are no particular
74 security concerns -- DLV RRs are just like any other DNS data.
76 Software using DLV RRs as part of DNSSEC validation will almost
77 certainly want to impose constraints on their use, but those
78 constraints are best left to be described by the documents that more
79 fully describe the particulars of how the records are used. At a
80 minimum, it would be unwise to use the records without some sort of
81 cryptographic authentication. More likely than not, DNSSEC itself
82 will be used to authenticate the DLV RRs. Depending on how a DLV RR
83 is used, failure to properly authenticate it could lead to
84 significant additional security problems including failure to detect
87 RFC 4034, Section 8, describes security considerations specific to
88 the DS RR. Those considerations are equally applicable to DLV RRs.
89 Of particular note, the key tag field is used to help select DNSKEY
90 RRs efficiently, but it does not uniquely identify a single DNSKEY
91 RR. It is possible for two distinct DNSKEY RRs to have the same
92 owner name, the same algorithm type, and the same key tag. An
93 implementation that uses only the key tag to select a DNSKEY RR might
94 select the wrong public key in some circumstances.
96 For further discussion of the security implications of DNSSEC, see
97 RFC 4033, RFC 4034, and RFC 4035.
99 4. IANA Considerations
101 IANA has assigned DNS type code 32769 to the DLV resource record from
102 the Specification Required portion of the DNS Resource Record Type
103 registry, as defined in [4].
105 The DLV resource record reuses the same algorithm and digest type
106 registries already used for the DS resource record, currently known
107 as the "DNS Security Algorithm Numbers" and "DS RR Type Algorithm
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116 RFC 4431 DLV Resource Record February 2006
119 5. Normative References
121 [1] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
122 "DNS Security Introduction and Requirements", RFC 4033,
125 [2] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
126 "Resource Records for the DNS Security Extensions", RFC 4034,
129 [3] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
130 "Protocol Modifications for the DNS Security Extensions",
131 RFC 4035, March 2005.
133 [4] Eastlake, D., Brunner-Williams, E., and B. Manning, "Domain Name
134 System (DNS) IANA Considerations", BCP 42, RFC 2929,
140 Internet Systems Consortium
142 Redwood City, CA 94063
145 EMail: Mark_Andrews@isc.org
150 7075 Samuel Morse Drive
151 Columbia, Maryland 21046
154 EMail: weiler@tislabs.com
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172 RFC 4431 DLV Resource Record February 2006
175 Full Copyright Statement
177 Copyright (C) The Internet Society (2006).
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