As per Relevance of the word services, we have this rfc below:
Network Working Group C.
Request for Comments: 2937 Sun Microsystems, Inc
Category: Standards Track September 2000
The Name Service Search Option for
Status of this
This document specifies an Internet standards track protocol for
Internet community, and requests discussion and suggestions
improvements. Please refer to the current edition of the "
Official Protocol Standards" (STD 1) for the standardization
and status of this protocol. Distribution of this memo is unlimited
Copyright
Copyright (C) The Internet Society (2000). All Rights Reserved
This document defines a new Dynamic Host Configuration
(DHCP) option which is passed from the DHCP Server to the DHCP
to specify the order in which name services should be consulted
resolving hostnames and other information
The Dynamic Host Configuration Protocol (DHCP)[1] provides
framework for passing configuration information to hosts on a TCP/
network. RFC 2132 [2] allows DHCP servers to specify
information for various kinds of name services to be passed to
clients. Many clients use multiple name services and have
their own conventions that allow an individual host to express
order among the various name services with which lookups are done
However, no search order can be specified via DHCP. The purpose
this document is to allow DHCP servers to specify the search order
be used by DHCP clients. To avoid the need for inventing
maintaining a separate name space for this option, we rely on
existence of previously-defined DHCP options that specify the
address(es) of servers which provide name services whose order
wish to express
Smith Standards Track [Page 1]
RFC 2937 The Name Service Search Option for DHCP September 2000
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in
document are to be interpreted as described in RFC 2119 [3].
document also uses the following terms
"DHCP client
DHCP client or "client" is an Internet host using DHCP
obtain configuration parameters such as a network address
"DHCP server
A DHCP server or "server" is an Internet host that
configuration parameters to DHCP clients
Name Service Search Option
The code for this option is 117, and its minimum length is 2 bytes
A DHCP server SHOULD return, in its preferred order, the 16-bit
network byte order (big-endian [4]) integer option code for
name services (the earlier in the list, the more preferred the
service).
Code Length Name Service Search Order in
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 117 | Len | ns1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ns2 | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In the above diagram, ns1 and ns2 are 16-bit integers
to two DHCP options which specify the IP addresses of two
types of name server. The current list of name services and
DHCP option codes, taken from RFC 2132,
Name Service
Domain Name Server Option 6
Network Information Servers Option 41
NetBIOS over TCP/IP Name Server Option 44
Network Information Service+ Servers Option 65
Smith Standards Track [Page 2]
RFC 2937 The Name Service Search Option for DHCP September 2000
A name service option code of 0 is used to indicate that
client should refer to local naming information (e.g.,
/etc/hosts file on a UNIX machine).
A DHCP server wishing to express that a client should first
DNS, then NIS+, would
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 117 | 4 | 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 65 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DHCP Client
The DHCP client will use this option to create a search list
name resolution. The client may receive name services in
option that it does not support or has not been configured
access. Likewise, a client may receive an option that lists
services for which no corresponding DHCP option was supplied
Clients will interpret this option in a system-specific
whose specification is outside the scope of this document
Security
DHCP currently provides no authentication or security mechanisms
Potential exposures to attack are discussed in section 7 of the
protocol specification [1].
IANA
IANA has assigned a value of 117 for the DHCP option code
in this document
Smith Standards Track [Page 3]
RFC 2937 The Name Service Search Option for DHCP September 2000
[1] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
1997.
[2] Alexander, S. and R. Droms, "DHCP Options and BOOTP
Extensions", RFC 2132, March 1997.
[3] Bradner, S., "Key words for use in RFCs to indicate
levels", BCP 14, RFC 2119, March 1997.
[4] Cohen, D., "On Holy Wars and a Plea for Peace", Computer, IEEE
October 1981.
Author's
Carl
Sun Microsystems, Inc
901 San Antonio
Palo Alto, CA 94043
EMail: cs@Eng.Sun.
Smith Standards Track [Page 4]
RFC 2937 The Name Service Search Option for DHCP September 2000
Full Copyright
Copyright (C) The Internet Society (2000). All Rights Reserved
This document and translations of it may be copied and furnished
others, and derivative works that comment on or otherwise explain
or assist in its implementation may be prepared, copied,
and distributed, in whole or in part, without restriction of
kind, provided that the above copyright notice and this paragraph
included on all such copies and derivative works. However,
document itself may not be modified in any way, such as by
the copyright notice or references to the Internet Society or
Internet organizations, except as needed for the purpose
developing Internet standards in which case the procedures
copyrights defined in the Internet Standards process must
followed, or as required to translate it into languages other
English
The limited permissions granted above are perpetual and will not
revoked by the Internet Society or its successors or assigns
This document and the information contained herein is provided on
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
Funding for the RFC Editor function is currently provided by
Internet Society
Smith Standards Track [Page 5]
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.
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