DNS & MX questions

[redhelpdesk]

We have our main domain school.au and we have DNS mx records which point to our exchange server for that top level domain.

 

We want to create a new A record in DNS for a subdomain.schoo.au and have MX records for that specific subdmain pointing to different mail server.

 

How would we go about adding in more MX in the main dns entry? I Cant get my head round that part..

[EduTech]

We have our main domain school.au and we have DNS mx records which point to our exchange server for that top level domain.

 

We want to create a new A record in DNS for a subdomain.schoo.au and have MX records for that specific subdmain pointing to different mail server.

 

How would we go about adding in more MX in the main dns entry? I Cant get my head round that part..

 

In the admin console for your domain, is there an option to pick what domain you want to change the settings for? it's hard to explain as they all work different but techically when you add a subdomain you should then be able to manage that seperatly and then add MX Records in that.

 

Personally i point domains to servers via name server and then manage the DNS from there, as i cant do much with the domain registrar with regards to that.

 

and at work i use a smarthost so likewise no need to worry.

 

probably dont help much, but just thought i would mention it anyway mate.

[powdarrmonkey]

Every provider is different, check their FAQs or ask them.

[Chillibear]

As mentioned by EduTech, it really depends on the domain hosting you have ... web control panel of some sort or do you submit Bind records?

 

Essentially at the DNS level a different mail server (MX record) for a subdomain is trivial. In a typical (we'll use Bind since it's probably the most common domain server) record you'd have something like:

 

$TTL 3600
example.com.  IN SOA example.com. webmaster.example.com. (
                       1 ; Serial ; Increment by one after every change
                  3600 ; Refresh every hour
                    900 ; Retry every 15 minutes
             3600000 ; Expire 1000 hours
                  3600 ) ; Minimum 1 hour

   IN NS registrars-name-server-1.example.net.
   IN NS registrars-name-server-2.example.net.

   IN MX 10 mail.example.org.

   IN A 212.13.197.213
   www IN CNAME example.com.
   ftp IN CNAME example.com. 

 

Now what's not so clearly shown in that example is the MX record is actually for example.com, the domain being implicit in the Bind configuration because it's missing as the first bit of the line. So say we had a subdomain with a different mail server we would do something like this:

 

$TTL 3600
example.com.  IN SOA example.com. webmaster.example.com. (
   1 ; Serial ; Increment by one after every change
   3600 ; Refresh every hour
   900 ; Retry every 15 minutes
   3600000 ; Expire 1000 hours
   3600 ) ; Minimum 1 hour

       IN NS registrars-name-server-1.example.net.
       IN NS registrars-name-server-2.example.net.

       IN MX 10 mail.example.org.

       IN A 192.168.0.1
www IN CNAME example.com.
ftp    IN CNAME example.com. 
sub   IN A 192.168.0.2

sub.example.com.  IN MX 10 some-other-mail-server.example.net.

So all we've done is define a new record, type is MX again, but this one applies to the sub.example.com domain and points to another mail server.

 

Those extra entries could actually be in a different Bind record (and often if that's what you'd do for a fully fledged sub domain) If you do need to use Bind then the NetWidget - Book Stuff is a pretty good book, haven't got my copy to hand, but I think there is a chapter on MX sub-domains.

Edited March 1, 2010 by Chillibear
tried tidying up the code formatting