We're bouncing email to houston.rr.com due to the MX being set to localhost. clb@countzero:~$ host -t mx houston.rr.com houston.rr.com mail is handled by 10 localhost. Setting the MX to 127.0.0.1 seems like an odd way to handle the switch. <http://www.chron.com/disp/story.mpl/business/silverman/4842611.html> --Chris
On Jan 12, 2008, at 7:02 PM, Chris Boyd wrote:
We're bouncing email to houston.rr.com due to the MX being set to localhost.
clb@countzero:~$ host -t mx houston.rr.com houston.rr.com mail is handled by 10 localhost.
Setting the MX to 127.0.0.1 seems like an odd way to handle the switch.
<http://www.chron.com/disp/story.mpl/business/silverman/4842611.html>
houston.rr.com, amongst other domains, went away as part of the adelphia / comcast / roadrunner customer swap. http://blog.wordtothewise.com/index.php/2008/01/11/changes-at-roadrunner/ I tend to agree about the MX-localhost thing (MX 0 . would be better), but the domain is dead, jim, as far as email is concerned. Cheers, Steve
A bunch of roadrunner subdomains migrated over to comcast and those are dud. One operationally better way to go seems to be Mark Delany's mx0dot proposal, which started out as an internet draft, but seems to have lost momentum .. the concept is sound though. http://ietfreport.isoc.org/idref/draft-delany-nullmx That'd mean houston IN MX 0 . --srs On Jan 13, 2008 8:32 AM, Chris Boyd <cboyd@gizmopartners.com> wrote:
We're bouncing email to houston.rr.com due to the MX being set to localhost.
clb@countzero:~$ host -t mx houston.rr.com houston.rr.com mail is handled by 10 localhost.
Setting the MX to 127.0.0.1 seems like an odd way to handle the switch.
<http://www.chron.com/disp/story.mpl/business/silverman/4842611.html>
On Sun, 13 Jan 2008, Suresh Ramasubramanian wrote:
One operationally better way to go seems to be Mark Delany's mx0dot proposal, which started out as an internet draft, but seems to have lost momentum .. the concept is sound though.
Exim implements this convention. Tony. -- f.a.n.finch <dot@dotat.at> http://dotat.at/ HEBRIDES: CYCLONIC 5 TO 7, BUT GALE 8 OR SEVERE GALE 9 IN NORTH AND WEST. ROUGH OR VERY ROUGH. RAIN OR SQUALLY SHOWERS. MODERATE OR GOOD.
On Jan 13, 2008 9:55 PM, Tony Finch <dot@dotat.at> wrote:
On Sun, 13 Jan 2008, Suresh Ramasubramanian wrote:
One operationally better way to go seems to be Mark Delany's mx0dot proposal, which started out as an internet draft, but seems to have lost momentum .. the concept is sound though.
Exim implements this convention.
Er, the concept is DNS related .. totally MTA independent. Simply declaring that there is no MX record in a way that stops fallback to an A record. Exim would check for such. Other MTAs, even those that dont explicitly check for it, would try to deliver email and fail immediately, creating a 550 / NDN / whatever. Basically -
To indicate that a domain never accepts email, it advertises a solitary MX RR with a RDATA section consisting of an arbitrary preference number 0, and a dot terminated null string as the mail exchanger domain, to denote that there exists no mail exchanger for a domain.
The dot termination denotes that the null MX domain is considered to be absolute, and not relative to the origin of the zone, the behavior of dot termination and the formatting of this record is as described in STD13
--srs
On Mon, 14 Jan 2008, Suresh Ramasubramanian wrote:
On Jan 13, 2008 9:55 PM, Tony Finch <dot@dotat.at> wrote:
On Sun, 13 Jan 2008, Suresh Ramasubramanian wrote:
One operationally better way to go seems to be Mark Delany's mx0dot proposal, which started out as an internet draft, but seems to have lost momentum .. the concept is sound though.
Exim implements this convention.
Er, the concept is DNS related .. totally MTA independent. Simply declaring that there is no MX record in a way that stops fallback to an A record.
It's slightly more subtle than that. MTAs have to interpret MX records, so there is plenty of variation in semantics. If an MTA does not implement the "." convention then it will look up the root's AAAA and A records, which is stupid but should cause the message to bounce as desired. However if it does implement the convention (just like the "usage rules" for a SRV record target of "." in RFC 2782) then it can skip the address lookups and save the root some work. (It can also produce a better error message.) This really ought to be explained in draft-delany-nullmx. Note that an MTA can't rely on its recursive DNS server to populate the additional section of a DNS reply, because of the truncation rules in RFC 2181. So if the additional section is empty (as it would be for an MX target of ".") it must explicitly look up the address records to find out if they are really missing or were just truncated. So it's worth implementing the "." convention explicitly. (See also http://www1.ietf.org/mail-archive/web/ietf/current/msg49843.html for the IPv6 implications of truncated MX records.) Tony. -- f.a.n.finch <dot@dotat.at> http://dotat.at/ LUNDY FASTNET IRISH SEA: MAINLY SOUTHWESTERLY 6 TO GALE 8, OCCASIONALLY SEVERE GALE 9 IN LUNDY AND FASTNET. ROUGH OR VERY ROUGH. SQUALLY SHOWERS THEN RAIN. MODERATE OR GOOD, OCCASIONALLY POOR LATER.
On Jan 14, 2008 5:08 PM, Tony Finch <dot@dotat.at> wrote:
the "." convention then it will look up the root's AAAA and A records, which is stupid but should cause the message to bounce as desired. However if it does implement the convention (just like the "usage rules" for a SRV record target of "." in RFC 2782) then it can skip the address lookups and save the root some work. (It can also produce a better error message.) This really ought to be explained in draft-delany-nullmx.
The draft died. And I think this stuff about looking up A / AAAA for the root was certainly raised in the IETF sometime back. Not that there isnt enough junk traffic (and DDoS etc) coming the roots' way that this kind of single lookup would get lost in the general noise .. Might want to revive it and take it forward? I rather liked that draft (and Mark Delany cites me in the acknowledgements as I suggested a few wording changes for the definition of a null MX - dot terminated null string, STD13 etc, during his drafting of the document) --srs -- Suresh Ramasubramanian (ops.lists@gmail.com)
In article <bb0e440a0801141838r736462dey64094e555cd6d0a6@mail.gmail.com> you write:
On Jan 14, 2008 5:08 PM, Tony Finch <dot@dotat.at> wrote:
the "." convention then it will look up the root's AAAA and A records, which is stupid but should cause the message to bounce as desired. However if it does implement the convention (just like the "usage rules" for a SRV record target of "." in RFC 2782) then it can skip the address lookups and save the root some work. (It can also produce a better error message.) This really ought to be explained in draft-delany-nullmx.
The draft died. And I think this stuff about looking up A / AAAA for the root was certainly raised in the IETF sometime back. Not that there isnt enough junk traffic (and DDoS etc) coming the roots' way that this kind of single lookup would get lost in the general noise ..
Might want to revive it and take it forward? I rather liked that draft (and Mark Delany cites me in the acknowledgements as I suggested a few wording changes for the definition of a null MX - dot terminated null string, STD13 etc, during his drafting of the document)
--srs
-- Suresh Ramasubramanian (ops.lists@gmail.com)
There are lots of places in the DNS where "." makes sense as a null indicator. RP uses it today, as does SRV. MX should use it and fallback to A should be removed. It actually takes more cache space to record that a MX record does not exist than it takes to record that a A or AAAA record exists (SOA rdata is atleast 22 octets). draft-ietf-dnsop-default-local-zones used it for SOA RNAME but was changed under WG pressure. A and AAAA should use 0.0.0.0 and :: to indicate that a host exists but is not currently connected. Mark
On Jan 15, 2008 8:53 AM, Mark Andrews <Mark_Andrews@isc.org> wrote:
There are lots of places in the DNS where "." makes sense as a null indicator. RP uses it today, as does SRV. MX should use it and fallback to A should be removed. It
Fallback to A should be removed sure sounds like a plan. srs
Fallback to A should be removed sure sounds like a plan.
great idea. it will only break mail to 42% of the internet. http://en.wikipedia.org/wiki/Principle_of_least_astonishment randy
Fallback to A should be removed sure sounds like a plan.
great idea. it will only break mail to 42% of the internet.
Since there is no fallback to AAAA, in a few years it will break very little as most of the internet will have IPv6 MTA's (and hence MX's) for their mail domains. MX fallback to A should have had a sunset time added to it when it was originally proposed. It is, after all, only a transition strategy. We can still add a sunset clause. MTA's would lookup their own MX records for the mail domains they are configured as final delivery agents for and if not found log that there are missing MX records. Mark
http://en.wikipedia.org/wiki/Principle_of_least_astonishment
randy
-- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews@isc.org
On Tue, 15 Jan 2008, Mark Andrews wrote:
Since there is no [MX] fallback to AAAA
Wrong. http://www1.ietf.org/mail-archive/web/ietf/current/msg49841.html Tony. -- f.a.n.finch <dot@dotat.at> http://dotat.at/ FISHER GERMAN BIGHT: SOUTHERLY BECOMING CYCLONIC THEN WESTERLY 7 TO SEVERE GALE 9, OCCASIONALLY STORM 10 IN GERMAN BIGHT, DECREASING 6 TO GALE 8 LATER. ROUGH OR VERY ROUGH. RAIN. MODERATE.
On Tue, 15 Jan 2008, Randy Bush wrote:
Fallback to A should be removed sure sounds like a plan.
great idea. it will only break mail to 42% of the internet.
Randy's right, though it's email *from* 42% of the Internet that's the biggest problem. [rant about email from shitty php web forms elided] Tony. -- f.a.n.finch <dot@dotat.at> http://dotat.at/ SOUTHEAST ICELAND: NORTHEASTERLY VEERING SOUTHERLY 5 TO 7, PERHAPS GALE 8 LATER. MODERATE OR ROUGH, OCCASIONALLY VERY ROUGH LATER. WINTRY SHOWERS THEN RAIN. MODERATE OR GOOD.
I see roadrunner listens. frodo:~ dig +short houston.rr.com mx 0 . frodo:~ dig +short houston.rr.com txt "v=spf1 -all" --srs On Jan 13, 2008 8:55 AM, Suresh Ramasubramanian <ops.lists@gmail.com> wrote:
A bunch of roadrunner subdomains migrated over to comcast and those are dud.
One operationally better way to go seems to be Mark Delany's mx0dot proposal, which started out as an internet draft, but seems to have lost momentum .. the concept is sound though.
http://ietfreport.isoc.org/idref/draft-delany-nullmx
That'd mean
houston IN MX 0 .
--srs
On Jan 13, 2008 8:32 AM, Chris Boyd <cboyd@gizmopartners.com> wrote:
We're bouncing email to houston.rr.com due to the MX being set to localhost.
clb@countzero:~$ host -t mx houston.rr.com houston.rr.com mail is handled by 10 localhost.
Setting the MX to 127.0.0.1 seems like an odd way to handle the switch.
<http://www.chron.com/disp/story.mpl/business/silverman/4842611.html>
-- Suresh Ramasubramanian (ops.lists@gmail.com)
participants (6)
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Chris Boyd -
Mark Andrews -
Randy Bush -
Steve Atkins -
Suresh Ramasubramanian -
Tony Finch