draft-ietf-dnsop-respsize-12.txt   draft-ietf-dnsop-respsize-13.txt 
Internet Engineering Task Force P. Vixie Internet Engineering Task Force P. Vixie
Internet-Draft Internet Systems Consortium Internet-Draft Internet Systems Consortium
Intended status: Informational A. Kato Intended status: Informational A. Kato
Expires: September 15, 2011 Keio University/WIDE Project Expires: March 16, 2012 Keio University/WIDE Project
March 14, 2011 September 13, 2011
DNS Referral Response Size Issues DNS Referral Response Size Issues
draft-ietf-dnsop-respsize-12 draft-ietf-dnsop-respsize-13
Abstract Abstract
With a mandated default minimum maximum UDP message size of 512 With a mandated default minimum maximum UDP message size of 512
octets, the DNS protocol presents some special problems for zones octets, the DNS protocol presents some special problems for zones
wishing to expose a moderate or high number of authority servers (NS wishing to expose a moderate or high number of authority servers (NS
RRs). This document explains the operational issues caused by, or RRs). This document explains the operational issues caused by, or
related to this response size limit, and suggests ways to optimize related to this response size limit, and suggests ways to optimize
the use of this limited space. Guidance is offered to DNS server the use of this limited space. Guidance is offered to DNS server
implementors and to DNS zone operators. implementors and to DNS zone operators.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 15, 2011. This Internet-Draft will expire on March 16, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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resolvers support EDNS. resolvers support EDNS.
Since DNS responses include a copy of the request, the space Since DNS responses include a copy of the request, the space
available for response data is somewhat less than the full 512 available for response data is somewhat less than the full 512
octets. Negative responses are quite small, but for positive and octets. Negative responses are quite small, but for positive and
referral responses, every octet must be carefully and sparingly referral responses, every octet must be carefully and sparingly
allocated. While the response size of positive responses is also a allocated. While the response size of positive responses is also a
concern in [RFC3226], this document specifically addresses referral concern in [RFC3226], this document specifically addresses referral
response size. response size.
EDNS deployment eleven years after the publication of [RFC2671] has While more than twelve years passed since the publication of EDNS0
reached approximately 65% of the client population as measured at one document[RFC2671], approximately 65% of the clients support it as
root name server and this fraction has not changed in recent years. observed at a root name server and this fraction has not changed in
The long tail of EDNS deployment may eventually be measured in recent few years. The long tail of EDNS deployment may eventually be
decades. measured in decades.
Even if EDNS deployment reached 100% of all DNS initiators and Even if EDNS deployment reached 100% of all DNS initiators and
responders there will still be cases when path MTU limitations or IP responders there will still be cases when path MTU limitations or IP
fragmentation/reassembly problems in firewalls and other middleboxes fragmentation/reassembly problems in firewalls and other middleboxes
will cause EDNS failures which leads to non-extended DNS retries. A will cause EDNS failures which leads to non-extended DNS retries. A
smaller referral response will always be better than a larger one if smaller referral response will always be better than a larger one if
the same end result can be achieved either way. the same end result can be achieved either way.
2. Delegation Details 2. Delegation Details
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Authors' Addresses Authors' Addresses
Paul Vixie Paul Vixie
Internet Systems Consortium Internet Systems Consortium
950 Charter Street 950 Charter Street
Redwood City, CA 94063 Redwood City, CA 94063
US US
Phone: +1 650 423 1300 Phone: +1 650 423 1300
Email: paul@vix.com Email: vixie@isc.org
Akira Kato Akira Kato
Keio University/WIDE Project Keio University/WIDE Project
Graduate School of Media Design, 4-1-1 Hiyoshi Graduate School of Media Design, 4-1-1 Hiyoshi
Kohoku, Yokohama 223-8526 Kohoku, Yokohama 223-8526
JP JP
Phone: +81 45 564 2490 Phone: +81 45 564 2490
Email: kato@wide.ad.jp Email: kato@wide.ad.jp
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