Re: MX and A records? by Todd
Todd
Sat Sep 11 21:17:53 CDT 2004
**please remember, these were just some possibilites that I could think of
off the top of my head.**
to answer your questions about the ISP hosting the mail, sure an Exch server
could be getting the mail or the clients could POP to the ISP.
If the A record and the MX record domains are the same name, most of the
time yes the mail is hosted in-house, BUT not always.
2 scenarios where it could be different:
lets say my domain is todd.com. i host my own webserver but my mail is
hosted by my ISP (weird but hey this is a scenario). my A record resolved
todd.com to my firewall. the mx record for todd.com reads todd.com pref = 5
mail exchanger = mail.isp.com then mail.isp.com resolves to the IP of the
mail server located at my ISP. they have it setup to recieve mail for
todd.com. so my A record will list my IP and the MX record will list the
ISP's IP.
other scenario is like my real email domain. our web domain and our email
domains are different. our A record is for one domain and the mx record
lists a different domain. so the names are different but go to the same
place.
an A records, CNAME, MX records are all different types of DNS records. DNS
records can be very simple or pretty complex depending on how much equipment
you have sitting on the internet and need name resolution for it.
just remember DNS is nothing more than a name to ip address translation and
vice versa.
Todd
"Andrew" <RelayPath@yahoo.com> wrote in message
news:10k74jnglkpd293@corp.supernews.com...
> When you say the ISP is hosting their mail does that mean mail is kept on
> the ISP's server and collected through Exch55 by dial-up? So if I am
> understanding right, 123.com holds mail for ABC.com to collect via
> POP3/IMAP?
>
> Now if company had a A record with the same domain name as the MX record
> domain name then does this mean mail is hosted in-house versus at the ISP
> like the example of ABC.123.com?
>
> Thanks again for helping me understanding this.
>
> "Todd" <Todd@discussions.microsoft.com> wrote in message
> news:F0823A24-6337-4BE8-AC7F-41E1BC5D71AB@microsoft.com...
>> ok, basically a mx record holds the domain name, a mx pref. & name of the
>> mail server or firewall (for this we will say its a mail server). then
>> it
>> also provides a name resolution to the mail server. if there are
>> multiple
> mx
>> records there will be multiple names listed below.
>>
>> probably goes like this:
>> ABC.com is thier domain and someone else like a parent company or an ISP
>> could be hosting thier mail. the company hosting the mail is 123.com.
>> the
>> name of the mail server for abc.com is abc.123.com. abc is the mail
>> server
>> name and it is part of the 123.com domain making it abc.123.com
>>
>> in the first line abc.com is the domain you requested, 5 is the mx pref.,
>> abc.123.com is the actual mail server name.
>>
>> the second line abc.123.com = xx.xx.xx.xx (whatever the IP is for that
>> device) this is so the requesting host can find the mail server to talk
> to
>> it.
>>
>> you asked if it should read mail.abc.com? it would if abc.com was the
>> parent domain and the mail server name was mail. the second line should
>> always be the same as what is listed and the mail exchanger in the first
>> line.
>>
>> Todd
>>
>>
>>
>> "Andrew" wrote:
>>
>> > Hi,
>> >
>> > I have a question about MX and A records. When I do a MX record lookup
> for a
>> > certain company say [ABC.com] I recieve the following output:
>> >
>> > ABC.com MX preference = 5, mail exchanger = ABC.123.com
>> >
>> > ABC.123.com internet address = 206.213.53.17
>> >
>> > My question is, where does the 123.com come from for the MX record?
> Should
>> > the domain on first line at the end read [mail.ABC.com] and the second
> line
>> > also read [mail.ABC.com] for the A record? Is this some kind of
>> > forward?
> I
>> > hope this makes sense? Please explain.
>> >
>> >
>> >
>
>