As per Relevance of the word multicast, we have this rfc below:
Network Working Group W.
Request for Comments: 1788
Category: Experimental April 1995
ICMP Domain Name
Status of this
This document defines an Experimental Protocol for the
community. This does not specify an Internet standard of any kind
Discussion and suggestions for improvement are requested
Distribution of this memo is unlimited
IESG Note
An Internet Engineering Steering Group comment from the co-
Director for IPng: Please note well that this memo is an
product of the author. It presents one view of the IN-
mechanism, motivated by discussion in the IPNG WG of the
of secure, dynamic update of the reverse tree. Other IETF
and ongoing standards work on this area will be found in the IP
Generation (ipngwg), DNS IXFR, Notification, and Dynamic
(dnsind), DNS Security (dnssec) working groups
This document specifies ICMP messages for learning the
Qualified Domain Name associated with an IP address
Simpson [Page 1]
RFC 1788 ICMP Domain Name April 1995
Table of
1. Introduction .......................................... 2
1.1 Direct Query .................................... 3
1.2 Multicast ....................................... 3
1.3 Domain Names .................................... 3
1.4 Messages ........................................ 4
2. Domain Name Request ................................... 4
3. Domain Name Reply ..................................... 5
SECURITY CONSIDERATIONS ...................................... 6
REFERENCES ................................................... 6
ACKNOWLEDGEMENTS ............................................. 7
AUTHOR'S ADDRESS ............................................. 7
1.
The Domain Name System (DNS) is described in [RFC-1034]. The IN-
domain of the DNS is specified [RFC-1035] to perform address
domain name resolution, and to facilitate queries to locate
gateways (routers) on a particular network in the Internet
Neither function has been remarkably successful. The IN-ADDR
is not reliably populated
As multiple routers were used at boundaries and within networks,
IN-ADDR mechanism was found to be inadequate. The location
routers by hosts is now performed using "ICMP Router
Messages" [RFC-1256].
As network numbers migrated to "classless" routing and aggregation
the IN-ADDR delegation granularity has fragmented, and
overlapping administration. The "reverse" IN-ADDR
frequently does not follow the same delegation as the "forward
domain name tree. This structure is not amenable to
secure updating of the DNS
As application servers have appeared which require the Domain
for user interaction and security logging, the IN-ADDR servers
been inundated with queries. This produces long user visible
at the initiation of sessions
Simpson [Page 2]
RFC 1788 ICMP Domain Name April 1995
1.1. Direct
This document proposes that each unicast address be queried
for its corresponding Domain Name. This has the advantages that
naming is under the same administration as the address assignment
and the queries are distributed in the same fashion as IP routing
In effect, the routing is used to index the database
1.2.
Only a few well-known multicast addresses are populated in the IN
ADDR domain. The ephemeral nature of most multicast addresses is
conducive to cooperative secure updating of the DNS
However, the technique described here is not useful for
addresses. A query to a multicast address could result in a storm
replies. Most multicast groups are not named, or the member
are not configured with the name
The IN-ADDR method SHOULD continue to be used for reverse lookup
well-known multicast addresses in the range 224.0.0.0
224.0.255.255. Other multicast addresses are an issue for
study
1.3. Domain
Each Domain Name is expressed as a sequence of labels. Each label
represented as a one octet length field, followed by that number
octets. Since every Domain Name ends with the null label of
root, a Domain Name is terminated by a length byte of zero. The
significant two bits of every length octet must be '00', and
remaining six bits of the length field limit the label to 63
or less
When the most significant two bits of the length octet are '11',
length is interpreted as a 2 octet sequence, indicating an
from the beginning of the message (Type field). Further details
described in [RFC-1035] "Message Compression".
To simplify implementations, the total length of a Domain
(including label octets and label length octets) is restricted to 255
octets or less
Simpson [Page 3]
RFC 1788 ICMP Domain Name April 1995
1.4.
The datagram format and basic facilities are already defined for
[RFC-792].
Up-to-date values of the ICMP Type field are specified in the
recent "Assigned Numbers" [RFC-1700]. This document concerns
following values
37 Domain Name
38 Domain Name
2. Domain Name
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type 37
Code 0
Checksum The ICMP Checksum
Identifier If Code is zero, a value to aid in matching
and replies. For example, it might be used like
port in TCP or UDP to identify a session. May
zero
Sequence Number If Code is zero, a value to aid in matching
and replies. For example, the number might
incremented on each request sent. May be zero
A separate Domain Name Request is used for each IP
queried
An ICMP Domain Name Request received with a broadcast or
Destination MUST be silently discarded
On receipt of an ICMP error message, the implementations MAY
to resolve the Domain Name using the IN-ADDR method
Simpson [Page 4]
RFC 1788 ICMP Domain Name April 1995
3. Domain Name
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time-To-Live |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Names ...
+-+-+-+-+-+-+-+-
Type 38
Code 0
Checksum The ICMP Checksum
Identifier Copied from the request
Sequence Number Copied from the request
Time-To-Live The number of seconds that the name may be cached
For historic reasons, this value is a signed 2s
complement number
Names zero or more Fully Qualified Domain Names.
length of this field is determined from the
length of the datagram
When no names are known, the field is
(zero length), but the Reply is sent as
authoritative indication that no name is known
When more than one name is known, all such
SHOULD be listed
Any name which cannot entirely fit within the
MTU is not sent
The IP Source in a Reply MUST be the same as the IP Destination
the corresponding Request message
Every host and router MUST implement an ICMP Domain Name
function that receives Domain Name Requests and sends
Domain Name Replies
Simpson [Page 5]
RFC 1788 ICMP Domain Name April 1995
A host SHOULD also implement an application- layer interface
sending a Domain Name Request and receiving a Domain Name Reply,
diagnostic purposes
Security
A primary purpose of this specification is to provide a mechanism
address to name resolution which is more secure than the IN-
reverse tree. This mechanism is amenable to use of the IP
Protocols for authentication and privacy
Although the routing infrastructure to the Destination does
provide security in and of itself, it is as least as reliable
delivery of correspondence for the other sessions with the same peer
A DNS cryptographic signature, located by using the reply in
forward DNS direction, can be used to verify the reply itself
[RFC-792]
Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, USC/Information Sciences Institute,
1981.
[RFC-1034]
Mockapetris, P., "Domain Names - Concepts and Facilities",
STD 13, RFC 1034, USC/Information Sciences Institute
November 1987.
[RFC-1035]
Mockapetris, P., "Domain Names - Implementation
Specification", STD 13, RFC 1035, USC/
Sciences Institute, November 1987.
[RFC-1256]
Deering, S., Editor, "ICMP Router Discovery Messages",
RFC 1256, Xerox PARC, September 1991.
[RFC-1700]
Reynolds, J., and J. Postel, "ASSIGNED NUMBERS", STD 2,
RFC 1700, USC/Information Sciences Institute, October 1994.
Simpson [Page 6]
RFC 1788 ICMP Domain Name April 1995
The DNSIND and IPng Working Groups contributed substantial amounts
discussion
Additional comments should be submitted to
namedroppers@internic.net mailing list
Author's
Questions about this memo can also be directed to
William Allen
Computer Systems Consulting
1384
Madison Heights, Michigan 48071
Bill.Simpson@um.cc.umich.
bsimpson@MorningStar.
Simpson [Page 7]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
RFC documents can be found at I.E.T.F.
Relevance System Copyright © 2002 Spectrum WorldResearch
other technical nosh by ServerMasters Corporation
collaboration of BobX
