Improved Recursive DNS Server Selection for Multi-Interfaced Nodes
RFC 6731
Internet Engineering Task Force (IETF) T. Savolainen
Request for Comments: 6731 Nokia
Category: Standards Track J. Kato
ISSN: 2070-1721 NTT
T. Lemon
Nominum, Inc.
December 2012
Improved Recursive DNS Server Selection for Multi-Interfaced Nodes
Abstract
A multi-interfaced node is connected to multiple networks, some of
which might be utilizing private DNS namespaces. A node commonly
receives recursive DNS server configuration information from all
connected networks. Some of the recursive DNS servers might have
information about namespaces other servers do not have. When a
multi-interfaced node needs to utilize DNS, the node has to choose
which of the recursive DNS servers to use. This document describes
DHCPv4 and DHCPv6 options that can be used to configure nodes with
information required to perform informed recursive DNS server
selection decisions.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6731.
Copyright Notice
Copyright (c) 2012 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
Savolainen, et al. Standards Track [Page 1]
RFC 6731 RDNSS Selection for MIF Nodes December 2012
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Private Namespaces and Problems for Multi-Interfaced Nodes . . 4
2.1. Fully Qualified Domain Names with Limited Scopes . . . . . 4
2.2. Network-Interface-Specific IP Addresses . . . . . . . . . 5
2.3. A Problem Not Fully Solved by the Described Solution . . . 6
3. Deployment Scenarios . . . . . . . . . . . . . . . . . . . . . 7
3.1. CPE Deployment Scenario . . . . . . . . . . . . . . . . . 7
3.2. Cellular Network Scenario . . . . . . . . . . . . . . . . 7
3.3. VPN Scenario . . . . . . . . . . . . . . . . . . . . . . . 8
3.4. Dual-Stack Accesses . . . . . . . . . . . . . . . . . . . 8
4. Improved RDNSS Selection . . . . . . . . . . . . . . . . . . . 8
4.1. Procedure for Prioritizing RDNSSes and Handling
Responses . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. RDNSS Selection DHCPv6 Option . . . . . . . . . . . . . . 11
4.3. RDNSS Selection DHCPv4 Option . . . . . . . . . . . . . . 13
4.4. Scalability Considerations . . . . . . . . . . . . . . . . 15
4.5. Limitations on Use . . . . . . . . . . . . . . . . . . . . 15
4.6. Coexistence of Various RDNSS Configuration Tools . . . . . 16
4.7. Considerations on Follow-Up Queries . . . . . . . . . . . 17
4.8. Closing Network Interfaces and Local Caches . . . . . . . 17
5. Example of a Node Behavior . . . . . . . . . . . . . . . . . . 17
6. Considerations for Network Administrators . . . . . . . . . . 19
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
8. Security Considerations . . . . . . . . . . . . . . . . . . . 20
8.1. Attack Vectors . . . . . . . . . . . . . . . . . . . . . . 20
8.2. Trust Levels of Network Interfaces . . . . . . . . . . . . 21
8.3. Importance of Following the Algorithm . . . . . . . . . . 21
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
9.1. Normative References . . . . . . . . . . . . . . . . . . . 21
9.2. Informative References . . . . . . . . . . . . . . . . . . 22
Appendix A. Possible Alternative Practices for RDNSS Selection . 23
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