draft-ietf-dnsop-respsize-02.txt   draft-ietf-dnsop-respsize-03.txt 
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material or to cite them other than as "work in progress." material 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 (2005). All Rights Reserved. Copyright (C) The Internet Society (2006). All Rights Reserved.
Abstract Abstract
With a mandated default minimum maximum message size of 512 octets, With a mandated default minimum maximum message size of 512 octets,
the DNS protocol presents some special problems for zones wishing to the DNS protocol presents some special problems for zones wishing to
expose a moderate or high number of authority servers (NS RRs). This expose a moderate or high number of authority servers (NS RRs). This
document explains the operational issues caused by, or related to document explains the operational issues caused by, or related to
this response size limit. this response size limit.
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1 - Introduction and Overview 1 - Introduction and Overview
1.1. The DNS standard (see [RFC1035 4.2.1]) limits message size to 512 1.1. The DNS standard (see [RFC1035 4.2.1]) limits message size to 512
octets. Even though this limitation was due to the required minimum UDP octets. Even though this limitation was due to the required minimum UDP
reassembly limit for IPv4, it is a hard DNS protocol limit and is not reassembly limit for IPv4, it is a hard DNS protocol limit and is not
implicitly relaxed by changes in transport, for example to IPv6. implicitly relaxed by changes in transport, for example to IPv6.
1.2. The EDNS0 standard (see [RFC2671 2.3, 4.5]) permits larger 1.2. The EDNS0 protocol extension (see [RFC2671 2.3, 4.5]) permits
responses by mutual agreement of the requestor and responder. However, larger responses by mutual agreement of the requestor and responder.
deployment of EDNS0 cannot be expected to reach every Internet resolver However, deployment of EDNS0 cannot be expected to reach every Internet
in the short or medium term. The 512 octet message size limit remains resolver in the short or medium term. The 512 octet message size limit
in practical effect at this time. remains in practical effect at this time.
1.3. Since DNS responses include a copy of the request, the space 1.3. Since DNS responses include a copy of the request, the space
available for response data is somewhat less than the full 512 octets. available for response data is somewhat less than the full 512 octets.
For negative responses, there is rarely a space constraint. For Negative responses are quite small, but for positive and delegation
positive and delegation responses, though, every octet must be carefully responses, every octet must be carefully and sparingly allocated. This
and sparingly allocated. This document specifically addresses document specifically addresses delegation response sizes.
delegation response sizes.
2 - Delegation Details 2 - Delegation Details
2.1. A delegation response will include the following elements: 2.1. A delegation response will include the following elements:
Header Section: fixed length (12 octets) Header Section: fixed length (12 octets)
Question Section: original query (name, class, type) Question Section: original query (name, class, type)
Answer Section: (empty) Answer Section: (empty)
Authority Section: NS RRset (nameserver names) Authority Section: NS RRset (nameserver names)
Additional Section: A and AAAA RRsets (nameserver addresses) Additional Section: A and AAAA RRsets (nameserver addresses)
2.2. If the total response size would exceed 512 octets, and if the data 2.2. If the total response size would exceed 512 octets, and if the data
that would not fit belonged in the question, answer, or authority that would not fit belonged in the answer or authority section, then the
section, then the TC bit will be set (indicating truncation) which may TC bit will be set (indicating truncation) which may cause the requestor
cause the requestor to retry using TCP, depending on what information to retry using TCP, depending on what information was desired and what
was desired and what information was omitted. If a retry using TCP is information was omitted. If a retry using TCP is needed, the total cost
needed, the total cost of the transaction is much higher. (See [RFC1123 of the transaction is much higher. (See [RFC1123 6.1.3.2] for details
6.1.3.2] for details on the protocol requirement that UDP be attempted on the requirement that UDP be attempted before falling back to TCP.)
before falling back to TCP.)
2.3. RRsets are never sent partially unless truncation occurs, in which 2.3. RRsets are never sent partially unless TC bit set to indicate
case the final apparent RRset in the final nonempty section must be truncation. When TC bit is set, the final apparent RRset in the final
considered "possibly damaged". With or without truncation, the glue nonempty section must be considered "possibly damaged" (see [RFC2181
present in the additional data section should be considered "possibly 9]). With or without truncation, the glue present in the additional
incomplete", and requestors should be prepared to re-query for any data section should be considered "possibly incomplete", and requestors
damaged or missing RRsets. For multi-transport name or mail services, should be prepared to re-query for any damaged or missing RRsets. For
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IPv6 (AAAA) RRset even when an IPv4 (A) RRset is present.
this can mean querying for an IPv6 (AAAA) RRset even when an IPv4 (A) INTERNET-DRAFT June 2006 RESPSIZE
RRset is present.
2.4. DNS label compression allows a domain name to be instantiated only 2.4. DNS label compression allows a domain name to be instantiated only
once per DNS message, and then referenced with a two-octet "pointer" once per DNS message, and then referenced with a two-octet "pointer"
from other locations in that same DNS message. If all nameserver names from other locations in that same DNS message. If all nameserver names
in a message are similar (for example, all ending in ".ROOT- in a message are similar (for example, all ending in ".ROOT-
SERVERS.NET"), then more space will be available for uncompressable data SERVERS.NET"), then more space will be available for uncompressable data
(such as nameserver addresses). (such as nameserver addresses).
2.5. The query name can be as long as 255 characters of presentation 2.5. The query name can be as long as 255 characters of presentation
data, which can be up to 256 octets of network data. In this worst case data, which can be up to 256 octets of network data. In this worst case
scenario, the question section will be 260 octets in size, which would scenario, the question section will be 260 octets in size, which would
leave only 240 octets for the authority and additional sections (after leave only 240 octets for the authority and additional sections (after
deducting 12 octets for the fixed length header.) deducting 12 octets for the fixed length header.)
2.6. Average and maximum question section sizes can be predicted by the 2.6. Average and maximum question section sizes can be predicted by the
zone owner, since they will know what names actually exist, and can zone owner, since they will know what names actually exist, and can
measure which ones are queried for most often. For cost and performance measure which ones are queried for most often. For cost and performance
reasons, the majority of requests should be satisfied without truncation reasons, the majority of requests should be satisfied without truncation
or TCP retry. or TCP retry. Some queries to non-existing names can be large, however,
this is not a problem because the responses include a SOA record in the
authority section.
2.7. Requestors who deliberately send large queries to force truncation 2.7. Requestors who deliberately send large queries to force truncation
are only increasing their own costs, and cannot effectively attack the are only increasing their own costs, and cannot effectively attack the
resources of an authority server since the requestor would have to retry resources of an authority server since the requestor would have to retry
using TCP to complete the attack. An attack that always used TCP would using TCP to complete the attack. An attack that always used TCP would
have a lower cost. have a lower cost.
2.8. The minimum useful number of address records is two, since with 2.8. The minimum useful number of address records is two, since giving
only one address, the probability that it would refer to an unreachable only one address undermines the redundancy requirement. Implicit
server is too high. Truncation which occurs after two address records truncation (truncation without setting TC bit) which occurs after two
have been added to the additional data section is therefore less address records have been added to the additional data section is
operationally significant than truncation which occurs earlier. therefore less operationally significant than truncation which occurs
earlier.
2.9. The best case is no truncation. This is because many requestors 2.9. The best case is no truncation at all. This is because many
will retry using TCP by reflex, or will automatically re-query for requestors will retry using TCP by reflex, or will automatically re-
RRsets that are "possibly truncated", without considering whether the query for RRsets that are "possibly truncated", without considering
omitted data was actually necessary. whether the omitted data was actually necessary.
2.10. Each added NS RR for a zone will add a minimum of between 16 and 2.10. Each added NS RR for a zone will add a minimum of between 16 and
44 octets to every untruncated referral or negative response from the 44 octets to every untruncated referral or negative response from the
zone's authority servers (16 octets for an NS RR, 16 octets for an A RR, zone's authority servers (16 octets for an NS RR, 16 octets for an A RR,
and 28 octets for an AAAA RR), in addition to whatever space is taken by and 28 octets for an AAAA RR), in addition to whatever space is taken by
the nameserver name (NS NSDNAME and A/AAAA owner name). the nameserver name (NS NSDNAME as well as A or AAAA owner name).
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3 - Analysis 3 - Analysis
3.1. An instrumented protocol trace of a best case delegation response 3.1. An instrumented protocol trace of a best case delegation response
follows. Note that 13 servers are named, and 13 addresses are given. follows. Note that 13 servers are named, and 13 addresses are given.
This query was artificially designed to exactly reach the 512 octet This query was artificially designed to exactly reach the 512 octet
limit. limit.
;; flags: qr rd; QUERY: 1, ANS: 0, AUTH: 13, ADDIT: 13 ;; flags: qr rd; QUERY: 1, ANS: 0, AUTH: 13, ADDIT: 13
;; QUERY SECTION: ;; QUERY SECTION:
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F.GTLD-SERVERS.NET. 86400 A 192.35.51.30 ;; @400 F.GTLD-SERVERS.NET. 86400 A 192.35.51.30 ;; @400
G.GTLD-SERVERS.NET. 86400 A 192.42.93.30 ;; @416 G.GTLD-SERVERS.NET. 86400 A 192.42.93.30 ;; @416
H.GTLD-SERVERS.NET. 86400 A 192.54.112.30 ;; @432 H.GTLD-SERVERS.NET. 86400 A 192.54.112.30 ;; @432
I.GTLD-SERVERS.NET. 86400 A 192.43.172.30 ;; @448 I.GTLD-SERVERS.NET. 86400 A 192.43.172.30 ;; @448
J.GTLD-SERVERS.NET. 86400 A 192.48.79.30 ;; @464 J.GTLD-SERVERS.NET. 86400 A 192.48.79.30 ;; @464
K.GTLD-SERVERS.NET. 86400 A 192.52.178.30 ;; @480 K.GTLD-SERVERS.NET. 86400 A 192.52.178.30 ;; @480
L.GTLD-SERVERS.NET. 86400 A 192.41.162.30 ;; @496 L.GTLD-SERVERS.NET. 86400 A 192.41.162.30 ;; @496
M.GTLD-SERVERS.NET. 86400 A 192.55.83.30 ;; @512 M.GTLD-SERVERS.NET. 86400 A 192.55.83.30 ;; @512
;; MSG SIZE sent: 80 rcvd: 512 ;; MSG SIZE sent: 80 rcvd: 512
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3.2. For longer query names, the number of address records supplied will 3.2. For longer query names, the number of address records supplied will
be lower. Furthermore, it is only by using a common parent name (which be lower. Furthermore, it is only by using a common parent name (which
is GTLD-SERVERS.NET in this example) that all 13 addresses are able to is GTLD-SERVERS.NET in this example) that all 13 addresses are able to
fit. The following output from a response simulator demonstrates these fit. The following output from a response simulator demonstrates these
properties: properties:
% perl respsize.pl a.dns.br b.dns.br c.dns.br d.dns.br % perl respsize.pl a.dns.br b.dns.br c.dns.br d.dns.br
a.dns.br requires 10 bytes a.dns.br requires 10 bytes
b.dns.br requires 4 bytes b.dns.br requires 4 bytes
c.dns.br requires 4 bytes c.dns.br requires 4 bytes
d.dns.br requires 4 bytes d.dns.br requires 4 bytes
# of NS: 4 # of NS: 4
For maximum size query (255 byte): For maximum size query (255 byte):
if only A is considered: # of A is 4 (green) only A is considered: # of A is 4 (green)
if A and AAAA are condered: # of A+AAAA is 3 (yellow) A and AAAA are considered: # of A+AAAA is 3 (yellow)
if prefer_glue A is assumed: # of A is 4, # of AAAA is 3 (yellow) preferred-glue A is assumed: # of A is 4, # of AAAA is 3 (yellow)
For average size query (64 byte): For average size query (64 byte):
if only A is considered: # of A is 4 (green) only A is considered: # of A is 4 (green)
if A and AAAA are condered: # of A+AAAA is 4 (green) A and AAAA are considered: # of A+AAAA is 4 (green)
if prefer_glue A is assumed: # of A is 4, # of AAAA is 4 (green) preferred-glue A is assumed: # of A is 4, # of AAAA is 4 (green)
% perl respsize.pl ns-ext.isc.org ns.psg.com ns.ripe.net ns.eu.int % perl respsize.pl ns-ext.isc.org ns.psg.com ns.ripe.net ns.eu.int
ns-ext.isc.org requires 16 bytes ns-ext.isc.org requires 16 bytes
ns.psg.com requires 12 bytes ns.psg.com requires 12 bytes
ns.ripe.net requires 13 bytes ns.ripe.net requires 13 bytes
ns.eu.int requires 11 bytes ns.eu.int requires 11 bytes
# of NS: 4 # of NS: 4
For maximum size query (255 byte): For maximum size query (255 byte):
if only A is considered: # of A is 4 (green) only A is considered: # of A is 4 (green)
if A and AAAA are condered: # of A+AAAA is 3 (yellow) A and AAAA are considered: # of A+AAAA is 3 (yellow)
if prefer_glue A is assumed: # of A is 4, # of AAAA is 2 (yellow) preferred-glue A is assumed: # of A is 4, # of AAAA is 2 (yellow)
For average size query (64 byte): For average size query (64 byte):
if only A is considered: # of A is 4 (green) only A is considered: # of A is 4 (green)
if A and AAAA are condered: # of A+AAAA is 4 (green) A and AAAA are considered: # of A+AAAA is 4 (green)
if prefer_glue A is assumed: # of A is 4, # of AAAA is 4 (green) preferred-glue A is assumed: # of A is 4, # of AAAA is 4 (green)
(Note: The response simulator program is shown in Section 5.) (Note: The response simulator program is shown in Section 5.)
Here we use the term "green" if all address records could fit, or Here we use the term "green" if all address records could fit, or
"orange" if two or more could fit, or "red" if fewer than two could fit. "yellow" if two or more could fit, or "orange" if only one could fit, or
It's clear that without a common parent for nameserver names, much space "red" if no address record could fit. It's clear that without a common
would be lost. For these examples we use an average/common name size of parent for nameserver names, much space would be lost. For these
15 octets, befitting our assumption of GTLD-SERVERS.NET as our common examples we use an average/common name size of 15 octets, befitting our
parent name. assumption of GTLD-SERVERS.NET as our common parent name.
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We're assuming an average query name size of 64 since that is the We're assuming an average query name size of 64 since that is the
typical average maximum size seen in trace data at the time of this typical average maximum size seen in trace data at the time of this
writing. If Internationalized Domain Name (IDN) or any other technology writing. If Internationalized Domain Name (IDN) or any other technology
which results in larger query names be deployed significantly in advance which results in larger query names be deployed significantly in advance
of EDNS, then new measurements and new estimates will have to be made. of EDNS, then new measurements and new estimates will have to be made.
4 - Conclusions 4 - Conclusions
4.1. The current practice of giving all nameserver names a common parent 4.1. The current practice of giving all nameserver names a common parent
(such as GTLD-SERVERS.NET or ROOT-SERVERS.NET) saves space in DNS (such as GTLD-SERVERS.NET or ROOT-SERVERS.NET) saves space in DNS
responses and allows for more nameservers to be enumerated than would responses and allows for more nameservers to be enumerated than would
otherwise be possible. (Note that in this case it is wise to serve the otherwise be possible, since the common parent domain name only appears
common parent domain's zone from the same servers that are named within once in a DNS message and is referred to via "compression pointers"
it, in order to limit external dependencies when all your eggs are in a thereafter.
single basket.)
4.2. Thirteen (13) seems to be the effective maximum number of 4.2. Thirteen (13) seems to be the effective maximum number of
nameserver names usable traditional (non-extended) DNS, assuming a nameserver names usable traditional (non-extended) DNS, assuming a
common parent domain name, and given that response truncation is common parent domain name, and given that response truncation is
undesirable as an average case, and assuming mostly IPv4-only undesirable as an average case, and assuming mostly IPv4-only
reachability (only A RRs exist, not AAAA RRs). reachability (only A RRs exist, not AAAA RRs).
4.3. Adding two to five IPv6 nameserver address records (AAAA RRs) to a 4.3. Adding two to five IPv6 nameserver address records (AAAA RRs) to a
prototypical delegation that currently contains thirteen (13) IPv4 prototypical delegation that currently contains thirteen (13) IPv4
nameserver addresses (A RRs) for thirteen (13) nameserver names under a nameserver addresses (A RRs) for thirteen (13) nameserver names under a
common parent, would not have a significant negative operational impact common parent, would not have a significant negative operational impact
on the domain name system. on the domain name system.
5 - Source Code 5 - Source Code
#!/usr/bin/perl #!/usr/bin/perl
# #
# SYNOPSIS # SYNOPSIS
# repsize.pl [ -z zone ] fqdn_ns1 fqdn_ns2 ... # repsize.pl [ -z zone ] fqdn_ns1 fqdn_ns2 ...
# if all queries are assumed to have zone suffux, such as "jp" in # if all queries are assumed to have a same zone suffix,
# JP TLD servers, specify it in -z option # such as "jp" in JP TLD servers, specify it in -z option
# #
use strict; use strict;
use Getopt::Std; use Getopt::Std;
my ($sz_msg) = (512); my ($sz_msg) = (512);
my ($sz_header, $sz_ptr, $sz_rr_a, $sz_rr_aaaa) = (12, 2, 16, 28); my ($sz_header, $sz_ptr, $sz_rr_a, $sz_rr_aaaa) = (12, 2, 16, 28);
my ($sz_type, $sz_class, $sz_ttl, $sz_rdlen) = (2, 2, 4, 2); my ($sz_type, $sz_class, $sz_ttl, $sz_rdlen) = (2, 2, 4, 2);
my (%namedb, $name, $nssect, %opts, $optz); my (%namedb, $name, $nssect, %opts, $optz);
my $n_ns = 0; my $n_ns = 0;
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getopt('z', opts); getopt('z', %opts);
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if (defined($opts{'z'})) { if (defined($opts{'z'})) {
server_name_len($opts{'z'}); # just register it server_name_len($opts{'z'}); # just register it
} }
foreach $name (@ARGV) { foreach $name (@ARGV) {
my $len; my $len;
$n_ns++; $n_ns++;
$len = server_name_len($name); $len = server_name_len($name);
print "$name requires $len bytes\n"; print "$name requires $len bytes\n";
$nssect += $sz_ptr + $sz_type + $sz_class + $sz_ttl + $sz_rdlen + $len; $nssect += $sz_ptr + $sz_type + $sz_class + $sz_ttl + $sz_rdlen + $len;
} }
print "# of NS: $n_ns\n"; print "# of NS: $n_ns\n";
arsect(255, $nssect, $n_ns, "maximum"); arsect(255, $nssect, $n_ns, "maximum");
arsect(64, $nssect, $n_ns, "average"); arsect(64, $nssect, $n_ns, "average");
sub server_name_len { sub server_name_len {
my ($name) = @_; my ($name) = @_;
my (@labels, $len, $n, $suffix); my (@labels, $len, $n, $suffix);
$name =~ tr/A-Z/a-z/; $name =~ tr/A-Z/a-z/;
@labels = split(/./, $name); @labels = split(/\./, $name);
$len = length(join('.', @labels)) + 2; $len = length(join('.', @labels)) + 2;
for ($n = 0; $#labels >= 0; $n++, shift @labels) { for ($n = 0; $#labels >= 0; $n++, shift @labels) {
$suffix = join('.', @labels); $suffix = join('.', @labels);
return length($name) - length($suffix) + $sz_ptr return length($name) - length($suffix) + $sz_ptr
if (defined($namedb{$suffix})); if (defined($namedb{$suffix}));
$namedb{$suffix} = 1; $namedb{$suffix} = 1;
} }
return $len; return $len;
} }
sub arsect { sub arsect {
my ($sz_query, $nssect, $n_ns, $cond) = @_; my ($sz_query, $nssect, $n_ns, $cond) = @_;
my ($space, $n_a, $n_a_aaaa, $n_p_aaaa, $ansect); my ($space, $n_a, $n_a_aaaa, $n_p_aaaa, $ansect);
$ansect = $sz_query + 1 + $sz_type + $sz_class; $ansect = $sz_query + 1 + $sz_type + $sz_class;
$space = $sz_msg - $sz_header - $ansect - $nssect; $space = $sz_msg - $sz_header - $ansect - $nssect;
$n_a = atmost(int($space / $sz_rr_a), $n_ns); $n_a = atmost(int($space / $sz_rr_a), $n_ns);
$n_a_aaaa = atmost(int($space / ($sz_rr_a + $sz_rr_aaaa)), $n_ns); $n_a_aaaa = atmost(int($space / ($sz_rr_a + $sz_rr_aaaa)), $n_ns);
$n_p_aaaa = atmost(int(($space - $sz_rr_a * $n_ns) / $sz_rr_aaaa), $n_ns); $n_p_aaaa = atmost(int(($space - $sz_rr_a * $n_ns) / $sz_rr_aaaa), $n_ns);
printf "For %s size query (%d byte):\n", $cond, $sz_query; printf "For %s size query (%d byte):\n", $cond, $sz_query;
printf "if only A is considered: "; printf " only A is considered: ";
printf "# of A is %d (%s)\n", $n_a, &judge($n_a, $n_ns); printf "# of A is %d (%s)\n", $n_a, &judge($n_a, $n_ns);
printf "if A and AAAA are condered: "; printf " A and AAAA are considered: ";
printf "# of A+AAAA is %d (%s)\n", $n_a_aaaa, &judge($n_a_aaaa, $n_ns); printf "# of A+AAAA is %d (%s)\n", $n_a_aaaa, &judge($n_a_aaaa, $n_ns);
INTERNET-DRAFT July 2005 RESPSIZE printf " preferred-glue A is assumed: ";
INTERNET-DRAFT June 2006 RESPSIZE
printf "if prefer_glue A is assumed: ";
printf "# of A is %d, # of AAAA is %d (%s)\n", printf "# of A is %d, # of AAAA is %d (%s)\n",
$n_a, $n_p_aaaa, &judge($n_p_aaaa, $n_ns); $n_a, $n_p_aaaa, &judge($n_p_aaaa, $n_ns);
} }
sub judge { sub judge {
my ($n, $n_ns) = @_; my ($n, $n_ns) = @_;
return "green" if ($n >= $n_ns); return "green" if ($n >= $n_ns);
return "yellow" if ($n >= 2); return "yellow" if ($n >= 2);
return "orange" if ($n == 1); return "orange" if ($n == 1);
return "red"; return "red";
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Security Considerations Security Considerations
The recommendations contained in this document have no known security The recommendations contained in this document have no known security
implications. implications.
IANA Considerations IANA Considerations
This document does not call for changes or additions to any IANA This document does not call for changes or additions to any IANA
registry. registry.
IPR Statement Acknowledgement The authors thank Peter Koch and Rob Austein for their
valuable comments and suggestions.
Copyright (C) The Internet Society (2005). This document is subject to Refrenaces
the rights, licenses and restrictions contained in BCP 78, and except as
set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on an [RFC1035] Mockapetris, P.V., "Domain names - implementation and
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR specification", RFC1035, November 1987.
IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
INTERNET-DRAFT July 2005 RESPSIZE [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts -
Application and Support", RFC1123, October 1989.
[RFC2181] Elz, R., Bush, R., "Clarifications to the DNS Specification",
RFC2181, July 1997.
[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC2671,
August 1999.
INTERNET-DRAFT June 2006 RESPSIZE
Authors' Addresses Authors' Addresses
Paul Vixie Paul Vixie
950 Charter Street 950 Charter Street
Redwood City, CA 94063 Redwood City, CA 94063
+1 650 423 1301 +1 650 423 1301
vixie@isc.org vixie@isc.org
Akira Kato Akira Kato
University of Tokyo, Information Technology Center University of Tokyo, Information Technology Center
2-11-16 Yayoi Bunkyo 2-11-16 Yayoi Bunkyo
Tokyo 113-8658, JAPAN Tokyo 113-8658, JAPAN
+81 3 5841 2750 +81 3 5841 2750
kato@wide.ad.jp kato@wide.ad.jp
Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors retain
all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR
IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in this
document or the extent to which any license under such rights might or
might not be available; nor does it represent that it has made any
independent effort to identify any such rights. Information on the
procedures with respect to rights in RFC documents can be found in BCP
78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an attempt
made to obtain a general license or permission for the use of such
INTERNET-DRAFT June 2006 RESPSIZE
proprietary rights by implementers or users of this specification can be
obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary rights
that may cover technology that may be required to implement this
standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgement
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
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