< draft-ietf-dnsext-rfc2782bis-00.txt		draft-ietf-dnsext-rfc2782bis-01.txt >
	Network Working Group A. Gulbrandsen		Network Working Group A. Gulbrandsen
	Category: INTERNET-DRAFT Trolltech AS		Category: INTERNET-DRAFT Trolltech AS
	Obsoletes: 2052 P. Vixie		Obsoletes: 2782 P. Vixie
	draft-ietf-dnsext-rfc2782bis-00.txt Internet Software Consortium		draft-ietf-dnsext-rfc2782bis-01.txt Internet Software Consortium
	November 16, 2000 L. Esibov		June 6, 2001 L. Esibov
	Expires: May 16, 2001 Microsoft Corp.		Expires: December 6, 2001 Microsoft Corp.
	A DNS RR for specifying the location of services (DNS SRV)		A DNS RR for specifying the location of services (DNS SRV)
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with all		This document is an Internet-Draft and is in full conformance with all
	provisions of Section 10 of RFC2026.		provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering Task		Internet-Drafts are working documents of the Internet Engineering Task
	Force (IETF), its areas, and its working groups. Note that other groups		Force (IETF), its areas, and its working groups. Note that other groups
	may also distribute working documents as Internet- Drafts.		may also distribute working documents as Internet- Drafts.
	skipping to change at page 1, line 33 ¶		skipping to change at page 1, line 33 ¶
	or to cite them other than as "work in progress."		or to cite them other than as "work in progress."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt		http://www.ietf.org/ietf/1id-abstracts.txt
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2000). All Rights Reserved.		Copyright (C) The Internet Society (2001). All Rights Reserved.
	Abstract		Abstract
	This document describes a DNS RR which specifies the location of the		This document describes a DNS RR which specifies the location of the
	server(s) for a specific protocol and domain.		server(s) for a specific protocol and domain.
	Overview and rationale		Overview and rationale
	Currently, one must either know the exact address of a server to		Currently, one must either know the exact address of a server to
	contact it, or broadcast a question.		contact it, or broadcast a question.
	skipping to change at page 6, line 50 ¶		skipping to change at page 6, line 50 ¶
	servers and connect to the preferred one:		servers and connect to the preferred one:
	Do a lookup for QNAME=_service._protocol.domain, QCLASS=IN,		Do a lookup for QNAME=_service._protocol.domain, QCLASS=IN,
	QTYPE=SRV.		QTYPE=SRV.
	If the reply is NOERROR, ANCOUNT>0 and there is at least one		If the reply is NOERROR, ANCOUNT>0 and there is at least one
	SRV RR which specifies the requested Service and Protocol in		SRV RR which specifies the requested Service and Protocol in
	the reply:		the reply:
	If there is precisely one SRV RR, and its Target is "."		If there is precisely one SRV RR, and its Target is "."
	(the root domain), abort.		(the root domain), abort and do not attempt lookup for
			QNAME=domain, QCLASS=IN, QTYPE=A.
	Else, for all such RR's, build a list of (Priority, Weight,		Else, for all such RR's, build a list of (Priority, Weight,
	Target) tuples		Target) tuples
	Sort the list by priority (lowest number first)		Sort the list by priority (lowest number first)
	Create a new empty list		Create a new empty list
	For each distinct priority level		For each distinct priority level
	While there are still elements left at this priority		While there are still elements left at this priority
	skipping to change at page 9, line 28 ¶		skipping to change at page 9, line 28 ¶
	"ns1.ip-provider.net." and "ns2" - again, "ip-provider.net." is		"ns1.ip-provider.net." and "ns2" - again, "ip-provider.net." is
	quoted and only needs to be counted once.		quoted and only needs to be counted once.
	120 bytes for the 6 address records (assuming IPv4 only) mentioned		120 bytes for the 6 address records (assuming IPv4 only) mentioned
	by the SRV and NS RR's.		by the SRV and NS RR's.
	IANA Considerations		IANA Considerations
	The IANA has assigned RR type value 33 to the SRV RR. No other IANA		The IANA has assigned RR type value 33 to the SRV RR. No other IANA
	services are required by this document.		services are required by this document.
	Changes from RFC 2052		Changes from RFC 2782
	This document obsoletes RFC 2052. The major change from that		This document obsoletes RFC 2782
	previous, experimental, version of this specification is that now the		Only editorial clarifications were made to this document. Namely
	protocol and service labels are prepended with an underscore, to
	lower the probability of an accidental clash with a similar name used		- it was clarified that "Weight" subsection refers to real "random
	for unrelated purposes. Aside from that, changes are only intended		number" rather than integer number;
	to increase the clarity and completeness of the document. This
	document especially clarifies the use of the Weight field of the SRV		- it was clarified that the "Name" used in the owner name of the SRV
	records.		record used in "The format of the SRV RR" section is a "Domain"
			name;
			- the "QNAME=_service._protocol.target" was replaced by
			"QNAME=_service._protocol.domain" in "Usage rules" section to
			eliminate a possibility of confusion with the Target field of the
			SRV record.
			- client's behavior when response to a query contains a single SRV
			RR and its Target is "." is clarified in "Usage rules" section.
	Security Considerations		Security Considerations
	The authors believe this RR to not cause any new security problems.		The authors believe this RR to not cause any new security problems.
	Some problems become more visible, though.		Some problems become more visible, though.
	- The ability to specify ports on a fine-grained basis obviously		- The ability to specify ports on a fine-grained basis obviously
	changes how a router can filter packets. It becomes impossible		changes how a router can filter packets. It becomes impossible
	to block internal clients from accessing specific external		to block internal clients from accessing specific external
	services, slightly harder to block internal users from running		services, slightly harder to block internal users from running
	skipping to change at page 12, line 7 ¶		skipping to change at page 12, line 7 ¶
	Levon Esibov		Levon Esibov
	Microsoft Corporation		Microsoft Corporation
	One Microsoft Way		One Microsoft Way
	Redmond, WA 98052		Redmond, WA 98052
	EMail: levone@microsoft.com		EMail: levone@microsoft.com
	Full Copyright Statement		Full Copyright Statement
	Copyright (C) The Internet Society (2000). All Rights Reserved.		Copyright (C) The Internet Society (2001). All Rights Reserved.
	This document and translations of it may be copied and furnished to		This document and translations of it may be copied and furnished to
	others, and derivative works that comment on or otherwise explain it		others, and derivative works that comment on or otherwise explain it
	or assist in its implementation may be prepared, copied, published		or assist in its implementation may be prepared, copied, published
	and distributed, in whole or in part, without restriction of any		and distributed, in whole or in part, without restriction of any
	kind, provided that the above copyright notice and this paragraph are		kind, provided that the above copyright notice and this paragraph are
	included on all such copies and derivative works. However, this		included on all such copies and derivative works. However, this
	document itself may not be modified in any way, such as by removing		document itself may not be modified in any way, such as by removing
	the copyright notice or references to the Internet Society or other		the copyright notice or references to the Internet Society or other
	Internet organizations, except as needed for the purpose of		Internet organizations, except as needed for the purpose of
End of changes. 6 change blocks.
	16 lines changed or deleted		26 lines changed or added
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