The Name Service Search Option for DHCP (RFC2937)
Original Publication Date: 2000-Sep-01
Included in the Prior Art Database: 2019-Feb-13
Internet Society Requests For Comment (RFCs)
This document defines a new Dynamic Host Configuration Protocol (DHCP) option which is passed from the DHCP Server to the DHCP Client to specify the order in which name services should be consulted when resolving hostnames and other information. [STANDARDS-TRACK]
Network Working Group C. Smith Request for Comments: 2937 Sun Microsystems, Inc. Category: Standards Track September 2000
The Name Service Search Option for DHCP
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document defines a new Dynamic Host Configuration Protocol (DHCP) option which is passed from the DHCP Server to the DHCP Client to specify the order in which name services should be consulted when resolving hostnames and other information.
The Dynamic Host Configuration Protocol (DHCP) provides a framework for passing configuration information to hosts on a TCP/IP network. RFC 2132  allows DHCP servers to specify configuration information for various kinds of name services to be passed to DHCP clients. Many clients use multiple name services and have crafted their own conventions that allow an individual host to express the order among the various name services with which lookups are done. However, no search order can be specified via DHCP. The purpose of this document is to allow DHCP servers to specify the search order to be used by DHCP clients. To avoid the need for inventing and maintaining a separate name space for this option, we rely on the existence of previously-defined DHCP options that specify the IP address(es) of servers which provide name services whose order we 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 this document are to be interpreted as described in RFC 2119 . This document also uses the following terms:
DHCP client or "client" is an Internet host using DHCP to obtain configuration parameters such as a network address.
A DHCP server or "server" is an Internet host that returns configuration parameters to DHCP clients.
Name Service Search Option Format
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 ) integer option code for the name services (the earlier in the list, the more preferred the name service).
Code Length Name Service Search Order in Sequence 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 | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...