Re: Exchange Reverse DNS

From: Tom Felts (tfelts_at_mckennalong.com)
Date: 03/19/05 

Date: Sat, 19 Mar 2005 15:05:05 -0500

Well, that is kinda what I suspected. It isn't really an exchange issue at
all...at least, not until we can cofirm connectivity.
Here is what I would do if I were in your shoes:

1. I would run trace routes from domain 1 to each of the other domains, and
save it to a file.
2. I would run trace routes from the other domains to domain 1, and save it
to a file(s).
3. I would run traceroutes from domain 2 to domain 3, (and so on) and save
to file. You should be able to see from the trace routes where the packets
are dying.

Armed with that info, I would contact your ISP, and persist in talking to
one of the routing guru's. Someone with the appropriate knowledge should be
able to resolve this fairly quickly.....

I don't know who your ISP is, but in my experience I usually have to
escalate 2 to 3 levels above the first guy that answers the
phone...hopefully your ISP is better that that....

Good luck. Let us know how it goes.

Oh, yah, from a command line in win2k its tracert ip.address This will
show you the hops the packets go through to get from one place to another.
I also would suspect the gateway, but it could be how they have the net mask
set as well....

"Jerry Whalley" <jerry@!acsl.ca> wrote in message
news:31uo315qv3thfel6812iduugtu3v80o3g5@4ax.com...
> Thanks again, Tom, for your patience and pointers,
>
> What I know now is that DOMAIN1 can e-mail or ping DOMAIN2, DOMAIN3
> and DOMAIN4. These latter three can also e-mail and ping DOMAIN1. But
> DOMAIN2, DOMAIN3 and DOMAIN4 cannot e-mail or ping each other. Either
> by IP or HOSTNAME!
>
> They all have the same Exchange Server setup with identical
> configurations with the same updates and service packs!
>
> They are all on the same ISP. They do have some differences at this
> ISP. See below. the 123 is not a real octet, as you know.
>
> DOMAIN1 is on a separate SUBNET with a different GATEWAY address!
>
> IP Mask Notes ...
> 123.123.123.0 255.255.255.128 Subnet Address
> 123.123.123.1 255.255.255.128 Gateway
> ...
> 123.123.123.115 255.255.255.128 DOMAIN1
> ...
> 123.123.123.127 255.255.255.128 Broadcast Address
>
> DOMAIN2, DOMAIN3 and DOMAIN4 are all on a different SUBNET from
> DOMAIN1 with a different GATEWAY address. But the SUBNET and GATEWAY
> addresses are identical amongst these three! See below...
>
> IP Mask Notes ...
> 123.123.123.128 255.255.255.128 Subnet Address
> 123.123.123.129 255.255.255.128 Gateway
> ...
> 123.123.123.195 255.255.255.128 DOMAIN2
> ...
> 123.123.123.197 255.255.255.128 DOMAIN3
> ...
> 123.123.123.252 255.255.255.128 DOMAIN4
> ...
> 123.123.123.255 255.255.255.128 Broadcast Address
>
> Perhaps a change from the same SUBNET might resolve these issues?
>
> A DNS Audit shows us the Reverse DNS pointers. which are now correctly
> resolving! As our ISP set them yesterday!
>
> # Generated by DNS Audit
> # Version 8.0.9
> # 19/03/2005 10:45:48 AM
> #
> # DNS Audit from 123.123.123.115 to 123.123.123.252
> # Filter : All IP Addresses in range
>
> "IP Address" "Reverse Resolution" "Forward Resolution"
> 123.123.123.115 DOMAIN1 123.123.123.115
> ...
> 123.123.123.195 DOMAIN2 123.123.123.195
> ...
> 123.123.123.197 DOMAIN3 123.123.123.197
> ...
> 123.123.123.252 DOMAIN4 123.123.123.252
>
> Thankyou for your time, Tom...
>
> On Sat, 19 Mar 2005 11:59:10 -0500, "Tom Felts"
> <tfelts@mckennalong.com> wrote:
>
>>Well, we need to drop into layer 2 fundamentals. Can you Ping domain 2
>>from
>>domain 1 by IP address? By domain name? If you cannot ping by IP, then
>>you
>>need to check ip's, gateways, etc. Tracert is your friend here.
>>
>>If you can ping by IP, but not by name, then it is DNS....
>>
>>
>>"Jerry Whalley" <jerry@!acsl.ca> wrote in message
>>news:d7km315gmklgg05nhs6p44rt0iojt4kovn@4ax.com...
>>> Thanks Tom,
>>>
>>> That link definitely helped narrow things down.
>>>
>>> I can telnet mail.domain1.ca 25 from mail.domain3.ca but not from
>>> mail.domain2.ca. Neither can mail.domain2.ca telnet to domain1.ca ...
>>>
>>> domain1 and domain2 cannot e-mail each other. Domain3 can e-mail or
>>> telnet to either. Domain1 and domain2 can telnet to domain3...
>>>
>>> So the link you sent explains further after establishing the telnet
>>> session. So, what do you think the next step ought to be?
>>>
>>> I have e-mailed the ISP of these domains to enter a reverse DNS PTR
>>> for these Servers...
>>>
>>> I was thinking that maybe there is a reverse DNS issue. I had them
>>> make a PTR (reverse DNS) record for each of these servers on their DNS
>>> servers?
>>>
>>> mail.domain1.bc.ca IN PTR 252.123.123.123.in-addr.arpa
>>>
>>> mail.domain2.ca IN PTR 195.123.123.123.in-addr.arpa
>>>
>>> mail.domain3.ca IN PTR 115.123.123.123.in-addr.arpa
>>>
>>> Thanks for your time, Tom...
>>>
>>>
>>>
>>> On Fri, 18 Mar 2005 16:41:08 -0500, "Tom Felts"
>>> <tfelts@mckennalong.com> wrote:
>>>
>>>>The procedures outlined here should help narrow the issue:
>>>>http://support.microsoft.com/kb/q153119/
>>>>
>>>>
>>>>"Jerry Whalley" <jerry@!acsl.ca> wrote in message
>>>>news:7ahm31dl2416gf2istgp5ve9q0q2k8j20o@4ax.com...
>>>>> Hi Gang,
>>>>>
>>>>> Well, I am flubbered on this one.
>>>>>
>>>>> I have two working Exchange 2003 Servers on different Domains and
>>>>> fixed IP's. One is on a W2k Server the other is integrated in
>>>>> SBS2003s. E-mail from other Domains and myself on a different Domain
>>>>> are passing through to the intended recipients. BUT, when either
>>>>> person@domain1.ca e-mails person@domain2.bc.ca either direction, they
>>>>> are bounced back...
>>>>>
>>>>> We are in the same bldg and are on the same ISP's subnet. But so am I
>>>>> with no issues at e-mailing either of these domains.
>>>>>
>>>>> Here is the NDR...
>>>>>
>>>>> From: System Administrator
>>>>> Sent: 18-Mar-05 9:51 AM
>>>>> To: person@domain1.ca
>>>>> Subject: Undeliverable:testing
>>>>>
>>>>> Your message did not reach some or all of the intended recipients.
>>>>>
>>>>> Subject: testing
>>>>>
>>>>> Sent: 2005-03-16 9:38 AM
>>>>>
>>>>> The following recipient(s) could not be reached:
>>>>>
>>>>> person@domain1.ca on 2005-03-18 9:51 AM
>>>>>
>>>>> Could not deliver the message in the time limit specified.
>>>>> Please retry or contact your administrator.
>>>>>
>>>>> <domain-server1.bc.ca #4.4.7>
>>>>>
>>>>> Anyone with some pointers on where to trouble-shoot this?
>>>>>
>>>>> Kind Regards,
>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>> Jerry Whalley
>>>>> A+ Network+ Security+ MCSA
>>>>> Network and Security Systems Professional
>>>>> Technical Support Team Leader
>>>>> Aboriginal Computer Solutions Ltd.
>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>
>>>
>>> Kind Regards,
>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>> Jerry Whalley
>>> A+ Network+ Security+ MCSA
>>> Network and Security Systems Professional
>>> Technical Support Team Leader
>>> Aboriginal Computer Solutions Ltd.
>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>
>
> Kind Regards,
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> Jerry Whalley
> A+ Network+ Security+ MCSA
> Network and Security Systems Professional
> Technical Support Team Leader
> Aboriginal Computer Solutions Ltd.
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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