RFC 8106
IPv6 Router Advertisement Options for DNS Configuration
RFC 8106: IPv6 Router Advertisement Options for DNS Configuration 🎀
okay so this is the doc that teaches IPv6 routers how to hand out DNS info in Router Advertisements 🌐✨ no DHCPv6 needed (lowkey iconic)
The title block, bestie:
- RFC number: 8106 💖
- Title: IPv6 Router Advertisement Options for DNS Configuration
- Authors: J. Jeong (Sungkyunkwan University), S. Park (Samsung Electronics), L. Beloeil (Orange), and S. Madanapalli (NTT Data) 🫶
- Category: Standards Track 👑
- Date: March 2017
- ISSN: 2070-1721
- Obsoletes: RFC 6106 💅
Abstract ✨
this doc specifies IPv6 Router Advertisement (RA) options, called "DNS RA options," so IPv6 routers can advertise a list of DNS Recursive Server Addresses and a DNS Search List to IPv6 hosts 🦋
it obsoletes RFC 6106 and defines a higher default value for the lifetime of the DNS RA options 🍓 why? to cut down on the chance the options expire on links with a pretty high packet loss rate. main character energy for reliability 💪
Status of This Memo 🌸
this is an Internet Standards Track document 👑
it's a product of the Internet Engineering Task Force (IETF) and represents the consensus of the IETF community 🫶 it got public review and was approved for publication by the Internet Engineering Steering Group (IESG). if you want more on Internet Standards, check out Section 2 of RFC 7841 📚
for the current status, any errata, and how to send feedback, go to http://www.rfc-editor.org/info/rfc8106 💜
Copyright Notice 💅
Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. 🌈
this doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents, which you can find at http://trustee.ietf.org/license-info (as they stood on the publication date). read them carefully, bestie, because they explain your rights and restrictions 🙈 any Code Components pulled out of this document must include Simplified BSD License text, as described in Section 4.e of the Trust Legal Provisions, and they come without warranty as described in the Simplified BSD License ⚖️
Table of Contents 🗺️
1. Introduction ....................................................3
1.1. Applicability Statements ...................................3
1.2. Coexistence of RA Options and DHCP Options for DNS
Configuration ..............................................4
2. Requirements Language ...........................................4
3. Terminology .....................................................4
4. Overview ........................................................5
5. Neighbor Discovery Extension ....................................5
5.1. Recursive DNS Server Option ................................6
5.2. DNS Search List Option .....................................7
5.3. DNS Configuration Procedure ................................8
5.3.1. Procedure in IPv6 Hosts .............................9
5.3.2. Warnings for DNS Options Configuration ..............9
6. Implementation Considerations ..................................10
6.1. DNS Repository Management .................................10
6.2. Synchronization between DNS Server List and
Resolver Repository .......................................11
6.3. Synchronization between DNS Search List and
Resolver Repository .......................................12
7. Security Considerations ........................................12
7.1. Security Threats ..........................................12
7.2. Recommendations ...........................................13
8. IANA Considerations ............................................13
9. References .....................................................14
9.1. Normative References ......................................14
9.2. Informative References ....................................14
Appendix A. Changes from RFC 6106 .................................17
Acknowledgements ..................................................18
Authors' Addresses ................................................191. Introduction ✨
the goal here is to standardize IPv6 Router Advertisement (RA) options, called DNS RA options, for DNS Recursive Server Addresses used for DNS name resolution on IPv6 hosts 🌸 it also covers a DNS Search List (DNSSL) of domain suffixes 💖
IPv6 Neighbor Discovery (ND) and IPv6 Stateless Address Autoconfiguration (SLAAC) already let fixed or mobile nodes get one or more IPv6 addresses, default routers, and some other parameters [RFC4861] [RFC4862] 🧚
manually configuring nomadic hosts every time they hop to a new network is basically impossible 🙈 a one-time static setup is possible, but it's not really ideal for general-purpose hosts like laptops. like, if a host ran its own recursive name server directly connected to the global DNS, locally defined namespaces would just not be available to it 💀
DNS info can also come from DHCPv6 [RFC3315] [RFC3736] [RFC3646] 🦋 BUT access to DNS is a fundamental requirement for almost every host, so SLAAC can't stand on its own as a deployment model in any practical network with zero DNS configuration support 😭
these issues aren't pressing in dual-stack networks as long as a DNS server is reachable on the IPv4 side, but they get way more critical with IPv6-only networks 🔥 so this document defines a mechanism based on DNS RA options that lets IPv6 hosts configure DNS automatically 💅
1.1. Applicability Statements 🌈
RA-based DNS configuration is a useful option in networks where an IPv6 host's address is autoconfigured through IPv6 SLAAC and either (i) there's no DHCPv6 infrastructure at all, or (ii) some hosts don't have a DHCPv6 client 🫶 the goal is full configuration of basic networking info for hosts without needing DHCPv6. however, networks that need to distribute extra info will probably use DHCPv6, and in those networks RA-based DNS configuration may not be needed 🙈
RA-based DNS configuration lets an IPv6 host grab its DNS configuration (that's the DNS Recursive Server Addresses and the DNSSL) for the link(s) it's connected to 🍓 and the host learns this DNS config from the very same RA message that provides the rest of the link's config. one message, two jobs, zero stress ✨
the advantages and disadvantages of the RA-based approach are covered in [RFC4339], along with other approaches like DHCP and well-known anycast addresses 📚
1.2. Coexistence of RA Options and DHCP Options for DNS Configuration 💜
there are two protocols for configuring DNS info on a host: the RA options in this document, and the DHCPv6 options in [RFC3646] 👑 they can be used together. the rules for deciding when to use stateful configuration mechanisms are in [RFC4861] 🦋
hosts conforming to this specification MUST extract DNS information from RA messages, unless static DNS configuration has been specified by the user. if DNS info is available from multiple RAs and/or from DHCP, the host MUST maintain an ordered list of this info, as specified in Section 5.3.1. no skipping this, bestie 🚨
2. Requirements Language 📝
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 🫶
3. Terminology 📖
this doc uses the terminology defined in [RFC4861] and [RFC4862]. on top of that, six new terms are defined below 🌸
- Recursive DNS Server (RDNSS): A server that provides a recursive DNS resolution service for translating domain names into IP addresses or resolving PTR records as defined in [RFC1034] and [RFC1035]. 🧚
- RDNSS Option: An IPv6 RA option to deliver the RDNSS information to IPv6 hosts [RFC4861]. 💖
- DNS Search List (DNSSL): The list of DNS suffix domain names used by IPv6 hosts when they perform DNS query searches for short, unqualified domain names. 🦋
- DNSSL Option: An IPv6 RA option to deliver the DNSSL information to IPv6 hosts. 🍓
- DNS Repository: Two data structures for managing DNS configuration information in the IPv6 protocol stack, in addition to the Neighbor Cache and Destination Cache for Neighbor Discovery [RFC4861]. The first data structure is the DNS Server List for RDNSS addresses, and the second is the DNSSL for DNS search domain names. 🗂️
- Resolver Repository: Configuration repository with RDNSS addresses and a DNSSL that a DNS resolver on the host uses for DNS name resolution. Examples are the UNIX resolver file (i.e.,
/etc/resolv.conf) and the Windows registry. 💻
4. Overview 🌈
this doc standardizes an ND option called the "RDNSS option," which contains the addresses of RDNSSes 🫶 it also standardizes an ND option called the "DNSSL option," which contains the DNSSL. this keeps parity with the DHCPv6 options and makes sure there's the functionality needed to figure out the search domains 🔍
the existing ND message (that's the RA) carries this info ✨ an IPv6 host can configure the IPv6 addresses of one or more RDNSSes through RA messages. with the RDNSS and DNSSL options, plus the Prefix Information option from the ND protocol [RFC4861] [RFC4862], a host can configure its IPv6 address and its DNS info at the same time, no DHCPv6 needed for DNS 🎀 the RA options for RDNSS and DNSSL can be used on any network that supports ND 💅
this approach needs manual configuration, or automatic mechanisms (like DHCPv6 or vendor-proprietary configuration mechanisms), to set up the DNS info in the routers that send the advertisements 🛠️ automatically configuring RDNSS addresses and a DNSSL in routers is out of scope for this document, so that's a different story, bestie 🙈
5. Neighbor Discovery Extension 🦋
the IPv6 DNS configuration mechanism in this document needs two ND options in Neighbor Discovery: (i) the RDNSS option and (ii) the DNSSL option 💜
5.1. Recursive DNS Server Option ✨
okay bestie, the RDNSS option is how a router hands out the IPv6 addresses of DNS servers inside an RA 💅 every address in one option shares the same Lifetime value. if you want different Lifetimes, you just send multiple RDNSS options 🎀 here's the layout:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Addresses of IPv6 Recursive DNS Servers :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Figure 1: RDNSS Option Format
Here's the breakdown of each field 🧚
Type: an 8-bit identifier for the RDNSS option type, assigned by IANA. For this option it's 25 🌸Length: an 8-bit unsigned integer. The length of the option (counting theTypeandLengthfields too) is measured in units of 8 octets. The minimum value is 3 if one IPv6 address is in the option, and every extra RDNSS address adds 2 more. The receiver uses this field to figure out how many IPv6 addresses are inside 👀Lifetime: a 32-bit unsigned integer. This is the maximum time in seconds (counted from when the packet arrives) that these RDNSS addresses MAY be used for name resolution. By default, the value ofLifetimeSHOULD be at least 3 * MaxRtrAdvInterval, where MaxRtrAdvInterval is the maximum RA interval defined in [RFC4861]. An all-ones value (0xffffffff) means infinity ♾️ and a value of zero means the RDNSS addresses MUST no longer be used 💀Addresses of IPv6 Recursive DNS Servers: one or more 128-bit IPv6 addresses of the RDNSSes. How many there are depends on theLengthfield. Specifically, the number of addresses equals (Length - 1) / 2 🫶
Note: the addresses for RDNSSes in the RDNSS option MAY be link-local addresses 🌈 link-local addresses SHOULD be registered in the Resolver Repository along with the link zone indices of the links that receive the RDNSS option(s) for them. The link-local addresses MAY be represented in the Resolver Repository with their link zone indices, using the textual format for scoped addresses described in [RFC4007]. When a resolver sends a DNS query to an RDNSS identified by a link-local address, it MUST use the corresponding link.
Now the reasoning behind the default Lifetime 🤓 the Router Lifetime field, set by AdvDefaultLifetime, defaults to 3 * MaxRtrAdvInterval as specified in [RFC4861]. So a default like that, or a bigger one, helps keep DNS options reliable even when RAs get lost on links with a fairly high packet loss rate. The ratio of AdvDefaultLifetime to MaxRtrAdvInterval is the number of unsolicited multicast RAs the router sends. Since DNS option entries can survive at most three consecutive RA losses that contain DNS options, that default Lifetime keeps them resilient in packet-loss environments. the planning is so cute 🥹
5.2. DNS Search List Option
the DNSSL option holds one or more domain names of DNS suffixes 🍓 all of the domain names share the same Lifetime value, and if you want different Lifetimes, you can send multiple DNSSL options. Here's the format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Domain Names of DNS Search List :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Figure 2: DNSSL Option Format
The fields 📋
Type: an 8-bit identifier for the DNSSL option type, assigned by IANA. For this option it's 31 💖Length: an 8-bit unsigned integer. The length of the option (counting theTypeandLengthfields) is measured in units of 8 octets. The minimum value is 2 if at least one domain name is in the option. TheLengthfield gets set to a multiple of 8 octets so it can fit all the domain names in theDomain Names of DNS Search Listfield 📏Lifetime: a 32-bit unsigned integer. This is the maximum time in seconds (counted from when the packet arrives) that these DNSSL domain names MAY be used for name resolution. It works the same way as the RDNSS option'sLifetime, so by default it SHOULD be at least 3 * MaxRtrAdvInterval. An all-ones value (0xffffffff) means infinity, and a value of zero means the DNSSL domain names MUST no longer be used ⭐Domain Names of DNS Search List: one or more domain names of the DNSSL, which MUST be encoded as described in Section 3.1 of [RFC1035]. That method represents each domain name as a sequence of labels ending in a zero octet, called a domain name representation. When there's more than one domain name, their representations are just concatenated one after another. For simple decoding, the domain names MUST NOT be encoded in the compressed form described in Section 4.1.4 of [RFC1035]. Because this field's size MUST be a multiple of 8 octets, the leftover octets (the ones not used by the domain name representations) MUST be padded with zeros, using the smallest multiple that fits the representations 🧸
5.3. DNS Configuration Procedure
configuring DNS through the RDNSS and DNSSL options works exactly the same way as it does for any other ND option [RFC4861] 🦋
5.3.1. Procedure in IPv6 Hosts
when an IPv6 host gets DNS options (that's RDNSS and DNSSL options) through RA messages, it handles them like this 💅
- The options get checked using the
Lengthfield. For RDNSS, theLengthvalue has to be greater than or equal to the minimum value (3) and satisfy(Length - 1) % 2 == 0. For DNSSL, theLengthvalue has to be greater than or equal to the minimum value (2). The RDNSS option also gets checked with theAddresses of IPv6 Recursive DNS Serversfield, meaning those addresses should be unicast addresses 🔍 - If the DNS options are valid, the host SHOULD copy the values of the options into the DNS Repository and the Resolver Repository, in order. Otherwise, the host MUST discard the options. Check Section 6 for the detailed procedure 🫧
if the DNS info from RDNSS and DNSSL can come from multiple sources, like RAs and DHCP, the IPv6 host SHOULD keep some DNS options from all of those sources 🌸 unless the discovery mechanism says otherwise, the exact number of addresses and domain names to keep is up to local policy and implementation choice, set as a local configuration option. However, when there are multiple sources, storing a total of at least three RDNSS addresses (or DNSSL domain names) from those sources is RECOMMENDED 🎀 the DNS options from RAs and DHCP SHOULD be stored in the DNS Repository and Resolver Repository so that DHCP info shows up there first, which means it takes precedence. So DNS info from DHCP beats DNS info from RAs for DNS queries 👑
and for DNS options announced by RAs: if some RAs use the Secure Neighbor Discovery (SEND) protocol [RFC3971] for RA security, those MUST be preferred over RAs that don't use SEND 🔐 DNS options announced by RAs via SEND MUST also be preferred over those announced by unauthenticated DHCP [RFC3118]. For a detailed look at SEND for DNS RA options, see Section 7 🧚
5.3.2. Warnings for DNS Options Configuration
okay, there are two warnings for DNS options configuration, and they're important 🚨 (i) warning for multiple sources of DNS options and (ii) warning for multiple network interfaces.
First up, multiple sources of DNS options (like RAs and DHCP). An IPv6 host can configure its IP addresses from these sources. In that case, you can't control how the host uses DNS information or which source addresses it uses to send DNS queries 😭 so configurations where different mechanisms for autoconfiguration give different information may cause problems. That's why the network administrator needs to carefully configure different DNS options across the multiple autoconfiguration mechanisms, to minimize the impact of those problems [DHCPv6-SLAAC].
Second, if different DNS information shows up on different network interfaces, the behavior can get inconsistent 🙈 the IETF worked on this for both DNS and other info obtained from multiple interfaces [RFC6418] [RFC6419], and standardized a DHCP-based solution for RDNSS selection on multi-interfaced nodes, described in [RFC6731] 🌈
6. Implementation Considerations
the implementation considerations in this document cover three things: (i) DNS repository management, (ii) synchronization between the DNS Server List and the Resolver Repository, and (iii) synchronization between the DNSSL and the Resolver Repository 🧠
Note: implementations updated according to this document will still interoperate with existing implementations that follow [RFC6106] 🫶 that's because the main change here is a longer default Lifetime for DNS options, to handle lossy links 🌈
6.1. DNS Repository Management ✨
Okay bestie, so for DNS repository management, the two data structures SHOULD be synchronized with the Resolver Repository 🫶: (i) the DNS Server List, which keeps the list of RDNSS addresses, and (ii) the DNSSL, which keeps the list of DNS search domain names. Each entry in these two lists is a pair of an RDNSS address (or DNSSL domain name) and an Expiration-time, and it breaks down like this:
- RDNSS address for DNS Server List: IPv6 address of the RDNSS that is available for recursive DNS resolution service in the network advertising the RDNSS option. 🌸
- DNSSL domain name for DNSSL: DNS suffix domain name that is used to perform DNS query searches for short, unqualified domain names. 🎀
- Expiration-time for DNS Server List or DNSSL: The time when this entry becomes invalid. The Expiration-time gets set to the value of the Lifetime field of the RDNSS option or DNSSL option plus the current time. Whenever a new RDNSS option with the same address (or DNSSL option with the same domain name) is received on the same interface as a previous RDNSS option (or DNSSL option), this field gets updated to have a new Expiration-time. Once the current time goes past the Expiration-time, the entry counts as expired, so it should not be used any more. 🥀 Also, the DNS information for the RDNSS and DNSSL options need not be dropped if the expiry of the RA router lifetime happens, because these options have their own lifetime values. ✨
6.2. Synchronization between DNS Server List and Resolver Repository 💅
When an IPv6 host gets info about multiple RDNSS addresses within a network (think campus network or company network) through an RA message with RDNSS option(s), it stores the RDNSS addresses (in order) in both the DNS Server List and the Resolver Repository. 🧚 The processing has two parts: (i) processing the RDNSS option(s) included in an RA message and (ii) handling expired RDNSSes. The processing of RDNSS option(s) goes like this:
- Step (a): Receive and parse the RDNSS option(s). For the RDNSS addresses in each RDNSS option, perform Steps (b) through (d).
- Step (b): For each RDNSS address, check the following: If the RDNSS address already exists in the DNS Server List and the RDNSS option's Lifetime field is set to zero, delete the corresponding RDNSS entry from both the DNS Server List and the Resolver Repository. This stops the RDNSS address from being used any more for certain reasons in network management, e.g., the termination of the RDNSS or a renumbering scenario. 😭 That is, the RDNSS can resign from its DNS service because the machine running the RDNSS is out of service intentionally or unintentionally. Also, in the renumbering scenario, the RDNSS's IPv6 address will be changed, so the previous RDNSS address should not be used any more. The processing of this RDNSS address is finished here. Otherwise, go to Step (c).
- Step (c): For each RDNSS address, if it already exists in the DNS Server List and the RDNSS option's Lifetime field is not set to zero, then just update the value of the Expiration-time field according to the procedure specified in the third bullet of Section 6.1. Otherwise, go to Step (d).
- Step (d): For each RDNSS address, if it does not exist in the DNS Server List, register the RDNSS address and Lifetime with the DNS Server List and then insert the RDNSS address as the first one in the Resolver Repository. In the case where the data structure for the DNS Server List is full of RDNSS entries (that is, has more RDNSSes than the sufficient number discussed in Section 5.3.1), delete from the DNS Server List the entry with the shortest Expiration-time (i.e., the entry that will expire first). The corresponding RDNSS address is also deleted from the Resolver Repository. 🍓 For the ordering of RDNSS addresses in an RDNSS option, the first RDNSS address in the RDNSS option becomes the first one in the Resolver Repository, the second RDNSS address in the option becomes the second one in the repository, and so on. This ordering lets the RDNSS addresses in the RDNSS option get preferred according to their order in the RDNSS option for DNS name resolution. The processing of these RDNSS addresses is finished here. 👑
The handling of expired RDNSSes is as follows: whenever an entry expires in the DNS Server List, the expired entry is deleted from the DNS Server List, and also the RDNSS address corresponding to that entry is deleted from the Resolver Repository. 💀
6.3. Synchronization between DNS Search List and Resolver Repository 🌈
When an IPv6 host gets info about multiple DNSSL domain names within a network through an RA message with DNSSL option(s), it stores the DNSSL domain names (in order) in both the DNSSL and the Resolver Repository. The processing of the DNSSL has two parts: (i) processing the DNSSL option(s) included in an RA message and (ii) handling expired DNSSLs. The processing of DNSSL option(s) is the same as the processing of RDNSS option(s) as described in Section 6.2. 🦋
7. Security Considerations 🔥
In this section, we analyze security threats related to DNS options and then make recommendations to cope with them. Let's get into it. 👀
7.1. Security Threats 💀
For the RDNSS option, an attacker could send an RA with a fraudulent RDNSS address, misleading IPv6 hosts into contacting an unintended DNS server for DNS name resolution. 😱 Also, for the DNSSL option, an attacker can let IPv6 hosts resolve a hostname without a DNS suffix into an unintended host's IP address with a fraudulent DNSSL. These attacks are similar to ND attacks specified in [RFC4861] that use Redirect or Neighbor Advertisement messages to redirect traffic to individual addresses of malicious parties. Not me getting chills 🙈
However, the security of these RA options for DNS configuration does not affect ND protocol security [RFC4861]. This is because learning DNS information via the RA options cannot be worse than learning bad router information via the RA options. Therefore, the vulnerability of ND is not worse and is a subset of the attacks that any node attached to a LAN can do. Lowkey a relief, ngl ✨
7.2. Recommendations 🫶
The Secure Neighbor Discovery (SEND) protocol [RFC3971] is designed as a security mechanism for ND. In this case, ND can use SEND to allow all the ND options, including the RDNSS and DNSSL options, to be automatically signed with digital signatures. 🔐
It is common for network devices such as switches to include mechanisms to block unauthorized ports from running a DHCPv6 server to provide protection from rogue DHCPv6 servers [RFC7610]. That means an attacker on other ports cannot insert bogus DNS servers using DHCPv6. The corresponding technique for network devices is RECOMMENDED to block rogue RA messages that include the RDNSS and DNSSL options from unauthorized nodes [RFC6104] [RFC6105]. 💖
An attacker may provide a bogus DNSSL option in order to cause the victim to send DNS queries to a specific DNS server when the victim queries non-FQDNs (fully qualified domain names). For this attack, the DNS resolver in IPv6 hosts can mitigate the vulnerability with the recommendations mentioned in [RFC1535], [RFC1536], and [RFC3646]. Protect your queries, periodt 💅
8. IANA Considerations 🎀
The RDNSS option defined in this document uses the IPv6 Neighbor Discovery Option type assigned by IANA as follows:
Option Name Type
-----------------------------------
Recursive DNS Server Option 25The DNSSL option defined in this document uses the IPv6 Neighbor Discovery Option type assigned by IANA as follows:
Option Name Type
-----------------------------------
DNS Search List Option 31These options are registered in the "IPv6 Neighbor Discovery Option Formats" registry [ICMPv6]. 🌸
9. References 📚
9.1. Normative References 🌷
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<http://www.rfc-editor.org/info/rfc4862>.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <http://www.rfc-editor.org/info/rfc1035>.
[RFC4007] Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and
B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,
DOI 10.17487/RFC4007, March 2005,
<http://www.rfc-editor.org/info/rfc4007>.9.2. Informative References 🦋
Okay bestie, these are the informative refs, the "go read this if you want the backstory" pile 📚✨ Here they are, exactly as written:
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<http://www.rfc-editor.org/info/rfc1034>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315,
July 2003, <http://www.rfc-editor.org/info/rfc3315>.
[RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol
(DHCP) Service for IPv6", RFC 3736, DOI 10.17487/RFC3736,
April 2004, <http://www.rfc-editor.org/info/rfc3736>.
[RFC3646] Droms, R., Ed., "DNS Configuration options for Dynamic
Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
DOI 10.17487/RFC3646, December 2003,
<http://www.rfc-editor.org/info/rfc3646>.
[RFC6106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
"IPv6 Router Advertisement Options for DNS Configuration",
RFC 6106, DOI 10.17487/RFC6106, November 2010,
<http://www.rfc-editor.org/info/rfc6106>.
[RFC4339] Jeong, J., Ed., "IPv6 Host Configuration of DNS Server
Information Approaches", RFC 4339, DOI 10.17487/RFC4339,
February 2006, <http://www.rfc-editor.org/info/rfc4339>.
[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
"SEcure Neighbor Discovery (SEND)", RFC 3971,
DOI 10.17487/RFC3971, March 2005,
<http://www.rfc-editor.org/info/rfc3971>.
[RFC3118] Droms, R., Ed., and W. Arbaugh, Ed., "Authentication for
DHCP Messages", RFC 3118, DOI 10.17487/RFC3118, June 2001,
<http://www.rfc-editor.org/info/rfc3118>.
[RFC6104] Chown, T. and S. Venaas, "Rogue IPv6 Router Advertisement
Problem Statement", RFC 6104, DOI 10.17487/RFC6104,
February 2011, <http://www.rfc-editor.org/info/rfc6104>.
[RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J.
Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105,
DOI 10.17487/RFC6105, February 2011,
<http://www.rfc-editor.org/info/rfc6105>.
[RFC7610] Gont, F., Liu, W., and G. Van de Velde, "DHCPv6-Shield:
Protecting against Rogue DHCPv6 Servers", BCP 199,
RFC 7610, DOI 10.17487/RFC7610, August 2015,
<http://www.rfc-editor.org/info/rfc7610>.
[RFC1535] Gavron, E., "A Security Problem and Proposed Correction
With Widely Deployed DNS Software", RFC 1535,
DOI 10.17487/RFC1535, October 1993,
<http://www.rfc-editor.org/info/rfc1535>.
[RFC1536] Kumar, A., Postel, J., Neuman, C., Danzig, P., and S.
Miller, "Common DNS Implementation Errors and Suggested
Fixes", RFC 1536, DOI 10.17487/RFC1536, October 1993,
<http://www.rfc-editor.org/info/rfc1536>.
[DHCPv6-SLAAC]
Liu, B., Jiang, S., Gong, X., Wang, W., and E. Rey,
"DHCPv6/SLAAC Interaction Problems on Address and
DNS Configuration", Work in Progress,
draft-ietf-v6ops-dhcpv6-slaac-problem-07, August 2016.
[RFC6418] Blanchet, M. and P. Seite, "Multiple Interfaces and
Provisioning Domains Problem Statement", RFC 6418,
DOI 10.17487/RFC6418, November 2011,
<http://www.rfc-editor.org/info/rfc6418>.
[RFC6419] Wasserman, M. and P. Seite, "Current Practices for
Multiple-Interface Hosts", RFC 6419, DOI 10.17487/RFC6419,
November 2011, <http://www.rfc-editor.org/info/rfc6419>.
[RFC6731] Savolainen, T., Kato, J., and T. Lemon, "Improved
Recursive DNS Server Selection for Multi-Interfaced
Nodes", RFC 6731, DOI 10.17487/RFC6731, December 2012,
<http://www.rfc-editor.org/info/rfc6731>.
[ICMPv6] IANA, "Internet Control Message Protocol version 6
(ICMPv6) Parameters",
<http://www.iana.org/assignments/icmpv6-parameters/>.Appendix A. Changes from RFC 6106 🎀
Okay, the glow-up page! ✨ Here's everything that changed from RFC 6106 ("IPv6 Router Advertisement Options for DNS Configuration"):
- This document allows a higher default lifetime for the DNS RA options than RFC 6106 did 💖 The reason is that options kept expiring way too often on links with a high rate of packet loss 😭 The old lower bound of
2 * MaxRtrAdvIntervalwas shown to cause exactly that problem, so this revision relaxes the lower bound and sets a higher default of3 * MaxRtrAdvInterval. It also adds some extra clarifications, because clarity is everything 🧚 - The text about generating a Router Solicitation message to keep the RDNSS info fresh before the RDNSS option expires has been removed 🙅♀️ The goal is to stop multicast traffic on the link from going up 🌸
- RDNSS addresses can now be global addresses or link-local addresses, not just global ones 🦋 Link-local RDNSS addresses should be registered in the Resolver Repository along with their corresponding link zone indices 💜
- RFC 6106 recommended that the number of RDNSS addresses learned and maintained through the RDNSS RA option be limited to three 🙃 This document drops that recommendation, so the number of RDNSS addresses to maintain is decided by an implementer's local policy ✨
- RFC 6106 recommended that the number of DNS search domains learned and maintained through the DNSSL RA option be limited to three 🙃 This document drops that too. When the set of unique DNSSL values are not equivalent, none of them may be ignored for hostname lookups, according to an implementer's local policy 👑
- The guidance on a specific implementation for synchronizing the DNS Repository and Resolver Repository in kernel space and user space has been removed 🍓
- The "SHOULD" and "RECOMMENDED" (RFC 2119) key words were removed from the recommendation of using SEND as a security mechanism for ND 🔥 Instead, SEND is now specified only as a possible security mechanism for ND 🫶
Acknowledgements 💜
Huge thank-yous to everyone who helped shape this document, it genuinely benefited from their inputs 🌈 The lineup: Robert Hinden, Pekka Savola, Iljitsch van Beijnum, Brian Haberman, Tim Chown, Erik Nordmark, Dan Wing, Jari Arkko, Ben Campbell, Vincent Roca, Tony Cheneau, Fernando Gont, Jen Linkova, Ole Troan, Mark Smith, Tatuya Jinmei, Lorenzo Colitti, Tore Anderson, David Farmer, Bing Liu, and Tassos Chatzithomaoglou. The authors sincerely appreciate every single one of their contributions 🫶
This document was also supported by an Institute for Information & communications Technology Promotion (IITP) grant funded by the Korean government (MSIP) [10041244, Smart TV 2.0 Software Platform] 🇰🇷✨
Authors' Addresses 🧚
Here are the people behind it, with their contact details exactly as published 💌
Jaehoon Paul Jeong
Department of Software
Sungkyunkwan University
2066 Seobu-Ro, Jangan-Gu
Suwon, Gyeonggi-Do 16419
Republic of Korea
Phone: +82 31 299 4957
Fax: +82 31 290 7996
Email: pauljeong@skku.edu
URI: http://iotlab.skku.edu/people-jaehoon-jeong.php
Soohong Daniel Park
Software R&D Center
Samsung Electronics
Seoul R&D Campus D-Tower, 56, Seongchon-Gil, Seocho-Gu
Seoul 06765
Republic of Korea
Email: soohong.park@samsung.com
Luc Beloeil
Orange
5 rue Maurice Sibille
BP 44211
44042 Nantes Cedex 1
France
Phone: +33 2 28 56 11 84
Email: luc.beloeil@orange.com
Syam Madanapalli
NTT Data
#H304, Shriram Samruddhi, Thubarahalli
Bangalore 560066
India
Phone: +91 959 175 7926
Email: smadanapalli@gmail.com📦 where this page comes from
- ietf: rfc8106 2017-03
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms