RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", September 2007

Note: This RFC has been updated by RFC 5942, RFC 6980, RFC 7048, RFC 7527, RFC 7559, RFC 8028, RFC 8319, RFC 8425, RFC 9131, RFC 9685, RFC 9762

Errata ID: 8055
Status: Held for Document Update
Type: Technical
Publication Format(s) : TEXT
Reported By: Richard Patterson
Date Reported: 2024-07-29
Held for Document Update by: Erik Kline
Date Held: 2025-05-13

Section 4.2 says:

Note: If neither M nor O flags are set, this indicates that no 
information is available via DHCPv6.

It should say:

Note: If neither M nor O flags are set, this indicates that no 
information is available via DHCPv6 from the router, or from 
other nodes that the router has been made aware of.

Notes:

M=0 does not prevent a node from attempting DHCPv6.

The router cannot definitively know that no other DHCPv6 servers exist.

RFC 8415 does not require M=1, with §18 providing other examples that may trigger a DHCP exchange.

--- AD notes ---

Right, the advertising router can only know about the things with which is was configured, ergo no unimpeachable statement about the availability or lack thereof of DHCPv6 can be made with protocol-guaranteed perfect correctness.

One possible revision that a future -bis document could consider might be as follows:

OLD:

Note: If neither M nor O flags are set, this indicates that no
information is available via DHCPv6.

NEW:

Note: If neither M nor O flags are set, this indicates that the advertising router,
and by extension its administrator(s), are neither aware of nor party to any
other information available via DHCPv6.

(or words to that effect).

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