Re: Exchange mailing to A records intermittently instead of MX records ???
- From: "Al Mulnick" <amulnick_No_SPAM@xxxxxxxxxxx>
- Date: Wed, 13 Jul 2005 13:47:30 -0400
Which version of Exchange 2000 are you using?
Some thoughts:
SMTP is designed to check for MX records first, and then if it can't find
one, it should resort to an A record. If that fails, it should die trying
and send a NDR.
1) if this just started happening, I'm guessing something changed. What is
your DNS architecture as it relates to Exchange VS's? i.e. is VS1 your
internal VS and does it use internal DNS? What about VS2?
Has there been any changes to the DNS architecture as of late? What about
firewalls?
It *sounds* like DNS lookups are failing. I know you checked that, but that
would be the behavior I would expect if DNS failed. You may consider using
netmon to trigger on some of the lookups and see if you're getting failures
there. Increase the logging as well.
2) help me understand why you chose the dual-nic/dual VS configuration. I'm
not a fan of that configuration, but I understand there can be times when
it's useful. I consider that configuration rarely worth the increased
complexity and troubleshooting effort.
3) Verify that your physical infrastructure is working correctly. NIC,
switches, hubs, firewalls, etc. should all be checked. Those failures could
easily be caused by physical issues.
al
"Denis" <denis@xxxxxxxxxx> wrote in message
news:Oo3NDt8hFHA.1252@xxxxxxxxxxxxxxxxxxxxxxx
> Actually, the information came from "Configuring SMTP in Microsoft
> Exchange 2000 Server", Chapter 4
> Can be found at:
> http://www.microsoft.com/downloads/details.aspx?familyid=7c3fffe1-3761-4e7a-b6ca-f31fe957c024&displaylang=en
>
>
> "Al Mulnick" <amulnick_No_SPAM@xxxxxxxxxxx> wrote in message
> news:eAoi1cwhFHA.1248@xxxxxxxxxxxxxxxxxxxxxxx
>> Which KB article?
>>
>> "Denis" <denis@xxxxxxxxxx> wrote in message
>> news:eAmK3zvhFHA.576@xxxxxxxxxxxxxxxxxxxxxxx
>>> We are experiencing very bizarre stuff on our exchange servers when
>>> mailing
>>> to external domains.
>>>
>>> SMTP delivery is working fine and then all of a sudden we start getting
>>> failure reports back.
>>> We've been digging around and tracking, and we find that all of a sudden
>>> the
>>> SMTP virtual server is trying to deliver to the IP address of the A
>>> record
>>> for the domain, instead of to the IP address of the MX record. As in
>>> most
>>> cases this is the web server, we get a response back indicating that the
>>> server cannot relay for that domain, which is normal.
>>>
>>> My question is: why does the SMTP connector decide to send to the A
>>> record
>>> all of a sudden, instead of to the MX record ???
>>> Can we tell exchange to only attempt mailing to MX records ?
>>>
>>> I looked into the DNS caches and the information is correct.
>>> I ran DNSDIAG on our Exchange servers, against the various destinations
>>> and
>>> on the various virtual SMTP servers, and they all come back with the
>>> appropriate MX information. I don't know where to look anymore.
>>>
>>> BTW: after awhile it will revert sending to the MX records, as if
>>> nothing
>>> happened ...
>>>
>>> Our Exchange servers are multihomed systems. There is a single SMTP
>>> Virtual
>>> Server (VS) connector for each NIC. The SMTP VS on the external
>>> connector
>>> looks at our internal DNS servers, while the SMTP VS on the internal
>>> connectors looks to external DNS servers. (Setup according to one of
>>> MS's KB
>>> articles).
>>>
>>> Any ideas ?
>>>
>>> Thanks.
>>> Denis.
>>>
>>>
>>>
>>
>>
>
>
.
- References:
- Prev by Date: Re: Exchange mailing to A records intermittently instead of MX records ???
- Next by Date: Re: smtp problem with Exch 2000
- Previous by thread: Re: Exchange mailing to A records intermittently instead of MX records ???
- Next by thread: Receiving gmail on my Blackberry
- Index(es):
Relevant Pages
|
