Re: General DNS config questions
- From: "Michael Dragone" <no.e-mail=less_spam>
- Date: Tue, 29 May 2007 17:55:58 -0400
Max, please read inline below.
"Max C" <maxc246@xxxxxxxxx> wrote in message news:1180473873.163616.296740@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Thanks for the reply, Michael.
The second DNS configuration you posted looks good to me. You would need to
change your SPF record to not include "a" however.
I must admit that SPF records are quite a mystery to me. I believe I
created that SPF Record with some sort of Wizard. Perhaps I need to
rerun the wizard.
When I set up DNS the way you said looked good, I could no longer
receive emails. Would that be because of the SPF Record including "a"
as you mentioned? Do I *really* need the SPF Record? Could I just
get rid of it all together?
You don't NEED it, although you really should have one. While you're working on this issue you might want to remove it; it's better to have no SPF record than one that's misconfigured.
My guess was that the reason I couldn't receive emails when set up as
per my second post was that the "@" host record was pointing to our
Web Server in an A Record. Of course, there was another "@" Record as
an MX record, which I thought would be OK, but my thought was that
maybe the A Record was overriding the MX record.
The "@" record you refer to simply means "this domain." By having both "@" and "www" resolvable in DNS you allow visitors to get to your website by typing either "domain.com" or "www.domain.com" in their browser's address bar.
In general, you shouldn't use CNAME records as they require two DNS lookups for a full resolution (the first to resolve the CNAME to its A record, then another to resolve the A record to its IP address). You can have as many A records as you want resolve to the same IP address.
If you convert your CNAME record for your Web server to an A record, your zone would look like this:
A records
@ www.xxx.yyy.36 (Web server)
mail www.xxx.yyy.37 (Exchange server)
www www.xxx.yyy.36 (Web server)
MX records
Priority Host Goes To
0 @ mail
A remote system attempting to send you mail will query DNS for all your MX record values and attempt delivery to the one with the highest priority (the *lowest* numerical value) first. A second DNS query will be made for A record of the hostname returned by the MX lookup (in your case your MX record indicates mail.domain.com) to obtain its IP address. Delivery will then be attempted to that IP address over port 25 (SMTP).
I don't think your delayed mail issue is DNS related though. Do you have
this problem with any domains OTHER than Hotmail?
Hotmail seems to be the worst, but other domains are having problems
as well. For some reason GMail almost never has the problem. As you
can guess, trying to get someone at Hotmail to work with me on the
issue is about as easy as running a marathon on the bottom of the
ocean. Yahoo Mail delays about 3 to 5 % of the time, cox.net about
20%. It's really hard to tell which domains have the problem the
worst because most of my users don't realize they've received a
delayed email.
Once you've got your DNS squared away (and like I said earlier I don't believe this is your issue - you can receive mail, albeit mail from some domains is delayed), and since it looks like you're using Exchange, you might want to repost this to one of the Exchange newsgroups so we can get some more Exchange expertise on this issue.
Thanks again,
Max.
On May 29, 3:17 pm, "Michael Dragone" <no.e-mail=less_spam> wrote:The second DNS configuration you posted looks good to me. You would need to
change your SPF record to not include "a" however.
I don't think your delayed mail issue is DNS related though. Do you have
this problem with any domains OTHER than Hotmail?
"Max C" <maxc...@xxxxxxxxx> wrote in message
news:1180455897.711483.189510@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> On May 29, 10:20 am, Max C <maxc...@xxxxxxxxx> wrote:
>> OK, here's the deal. For the past several months our company has been
>> receiving a LOT of delayed emails. Some by a few hours some by a few
>> days. As you can guess, this is a serious problem. I've tried
>> several things to resolve this situation:
>> 1 - call our ISP, who was taking care of DNS for us at the time. They
>> said they'd heard of others having the same issue, but that the DNS
>> records for our domains were configured properly.
>> 2 - take control of our DNS records by moving them to GoDaddy and
>> setting the records up myself.
>> 3 - put a sniffer between our ISP's router and our firewall to confirm
>> that delayed emails are *really* not making it to our network. (Turns
>> out, about 20 to 30% of hotmail emails always get delayed coming to
>> any of our domains, so sending a batch of 10 or 20 emails from hotmail
>> to one of our domains allowed me to see the raw data coming in through
>> the sniffer. There is no doubt that the emails that were delayed
>> coming in to a user's inbox did *not* make it to our network. Also,
>> interestingly enough, nearly 100% of emails from gmail make it through
>> without delay. I've tried this hotmail and gmail test with groups of
>> 10 to 20 single emails dozens of times. Gmail is always on time and
>> hotmail always has 20 to 30% delays.)
>> 4 - purchase a separate DSL line, ran it through our firewall and
>> pointed one of our domain names' MX record to the DSL line's IP info.
>> Hotmail emails to that domain name on the new DSL line were still
>> delayed.
>> So, as a last ditch effort, I thought it wouldn't hurt to post our DNS
>> record info to get some advice. I'm the first to admit that DNS is
>> not one of my strong points. Any advice on changes would be
>> appreciated.
>> _____________________________________________________________________________________
>> A records
>> Host Points To
>> @ WWW.XXX.YYY.37
>> mail WWW.XXX.YYY.37
>> exchange WWW.XXX.YYY.37
>> www WWW.XXX.YYY.36
>> ts2 WWW.XXX.YYY.42
>> CNAMES (Aliases)
>> Host Points To
>> smtp @
>> ts ts2
>> ftp @
>> MX (Mail Exchange)
>> Priority Host Goes To
>> 0 @ mail
>> TXT (Text)
>> Host TXT Value
>> @ v=spf1 a mx ptr ~all
>> _____________________________________________________________________________________
>> I read earlier today that @ should point to my web server >> (WWW.XXX.YYY.
>> 36) instead of my exchange server (WWW.XXX.YYY.37) and that www should
>> be a cname pointing to @. Could that be causing emails delays? I
>> tried making that change on one of our unused domain names, but then I
>> didn't receive emails at all.
>> Thanks for any insight at all.
>> Max.
> To add to my above config, I use godaddy.com for DNS config. Here's
> something I've been playing around with:
> I changed the following records as such:
> A Records
> Host Points To
> @ WWW.XXX.YYY.36 (web server)
> mail WWW.XXX.YYY.37 (exchange server)
> exchange WWW.XXX.YYY.37 (exchange server)
> CNAMES (Aliases)
> Host Points To
> www @
> MX (Mail Exchange)
> Priority Host Goes To
> 0 @ mail (A Record for exchange server)
> ________________________________________________________________________
> GoDaddy.com says that "@" simply refers to the domain name in
> question. So, I thought "maybe it would be OK to have the A record
> for @ pointing to the web server (WWW.XXX.YYY.36) and then a MX record
> for "@" pointing to the exchange server (WWW.XXX.YYY.37)
> It would appear that line of thinking was incorrect. When I set up my
> test domain as above, I could not receive emails to that test domain.
> Thanks for reading again.
> Max.
.
- Follow-Ups:
- Re: General DNS config questions
- From: Max C
- Re: General DNS config questions
- References:
- General DNS config questions
- From: Max C
- Re: General DNS config questions
- From: Max C
- Re: General DNS config questions
- From: Michael Dragone
- Re: General DNS config questions
- From: Max C
- General DNS config questions
- Prev by Date: Re: General DNS config questions
- Next by Date: Re: Why is e-mail being rejected when sending to an external domain?
- Previous by thread: Re: General DNS config questions
- Next by thread: Re: General DNS config questions
- Index(es):
Relevant Pages
|
Loading
