External DNS

[leco]

OK not sure about this one:

I have an Exchange 2010 installation (finally) the RBC have told me that I need to put something into my external DNS. Could some kind person tell me where I do this please?

[SYNACK]

Depends on who hosts your external DNS but the thing that they will be talking about is a MX record pointing to an A record (subdomain) that resolves to your external IP address so that mail servers know where to send any email for your domain name. You will need to have port mapping setup on your external router/firewall to point all port 25 traffic received to your exchange server.

 

Edit so you want to make sure you have an A record something like mail.yourdomain.school.uk pointing to your external IP and have the MX record point to mail.yourdomain.school.uk

 

You may need to contact whoever provides your internet or manages your domain name to get them to change it if you do not have access to it directly.

Edited June 29, 2010 by SYNACK

[Ric_]

You will either need to add forwarder entries into your DNS servers or use a smarthost to forward your mail for you. I suggest it might be the former since DNS was mentioned.

 

Configure a DNS server to use forwarders: Domain Name System(DNS) should give you an idea where to start.

[leco]

Currently all email is sent via an SMTP smarthost connector to the RBC (smtp.rbc.net) - this continues to be so. All inward mail is pushed from the LA (though I suspect it's the RBC really) directly to my Exchange server. New Exchange server so change of IP to push to.

 

The external DNS record points to what I think is a sub domain (mail.schoolname.laname.sch.uk) and is a CNAME to the RBC (rp1-wak.rbc.net)

 

Does that make any sense to you - cos it doesn't to me

Edited June 29, 2010 by leco

[SYNACK]

Not sure on that one as I have only dealt with directly connected ones so not to sure on the logistics of your setup.

[leco]

Not sure on that one as I have only dealt with directly connected ones so not to sure on the logistics of your setup.

Yea that's the problem with looking at MS reports and articles, they can't take local situations into account. Getting through the grid for anything is a pain to say the least.

[SYNACK]

It depends on how they have it setup I guess, they could have it chaining directly through using a DNS record inside their system which would point to your mail server inside the RBC WAN, as you had a 2003 server it is probably pointing to it at the moment. In this case you may be able to get the info by doing a nslookup {old exchange ip} on a system that uses the RBC DNS directly. This may give you the RBC side DNS entry that needs to be altered.

 

Alternatively they could have set it up as an SMTP pull type system where you need to configure your exchange server to talk to theirs and ask for any new mail. I have only heard about these systems so have no idea on where to start on that one. Your old mail server may yield some clues in its setup though so may be worth a look through to see if you can find anything fancy. SMTP outbound via a smarthost is realitivly common via a connector but as suggested by the name only handles outbound traffic not inbound.

[leco]

The new setting from the grid points to the new Exchange server IP - that's what the change request was for I think. The connectors on both my 2003 and 2010 have the same smtp settings. I just don't know where I'm supposed to put this new external DNS CNAME record.

[SYNACK]

What exactly is the external CNAME that you got, is it an internal rbc one or one for your school domain itself, if you already had the school domain setup to point to the RBC and the records have not changed so long as they changed their internal stuff it will probably just work. If its an internal one then I'm not sure.

[leco]

Message reads:

Put into the external DNS the following: mail.schoolname.leaname.sch.uk CNAME rp1-wak.rbcname.net

This will take effect between 2-3 hours as it needs this time to propogate.

 

(schoolname - leaname - and rbcname are given for my locations, I have changed them here for some anonymity)

[SYNACK]

As you had a server already setup that record may already exist, what you want to do is look at your existing DNS records and make sure that they already point to that location. In windows command prompt:

nslookup
set type=All
schoolname.leaname.sch.uk

and make sure that your current MX record points to rp1-wak.rbcname.net if not then you will need to talk to whoever manages your external DNS to make that change. You should be able to find out who manages it by using a whois lookup on the domain like the one on this page http://network-tools.com/ which should give your the administrative contact.

[leco]

OK the MX mail exchangers (there are two of them) are pointing to smpt1-wak.rbcname.net and smtp2.rbcname.net.

 

Questions then - would the person that looks after our school web site be the person to ask perhaps? Do both of the smtp records get changed or just one of them?

[PiqueABoo]

Around here all the zones under ".sch.uk" are on the RBCs (authoritative) name servers so they do it. This is context sensitive i.e. don't think you can avoid talking to your RBC or some other local school for information about how things work there.

[leco]

Not allowed to talk to the RBC direct - have to go through the LEA ICT helpdesk. They have passed on the email from the RBC and have said that's all they have to do since they don't support Exchange! Which I find less than helpful.

[PiqueABoo]

They have passed on the email from the RBC and have said that's all they have to do since they don't support Exchange! Which I find less than helpful.

 

Mmm.. some LAs are clearly much better than others then.

 

There is of course another interpretation to that message: Could that simply be the RBC (badly) informing you that they have added that CNAME i.e. you don't need to do anything?

 

If you do an nslookup of "mail.schoolname.leaname.sch.uk" (from home) what does it say?

[leco]

Can't find non-existent domain

[PiqueABoo]

You substituted in your real schoolname, laname etc?

[leco]

Yep certainly did.

 

And the email said "Please ask the school to put in their external DNS ..." so clearly I have to do something my end.

[PiqueABoo]

OK repeat the nslookup in SYNACKs post (in the code block) - look for "primary name server" and assuming you find it is that anything you recognise? That is the only place you can add that CNAME and if it's not a) a box you control, b) a box where you can logon to some web i/f and fiddle with that DNS zone, then I don't see how.

[SYNACK]

OK the MX mail exchangers (there are two of them) are pointing to smpt1-wak.rbcname.net and smtp2.rbcname.net.

 

Questions then - would the person that looks after our school web site be the person to ask perhaps? Do both of the smtp records get changed or just one of them?

 

Would just need to change one of them (the one with the lowest prefference number), the second is there as a failover incase the first one is inaccessable. If the preffreence numbers are equal then it will just load balance between them. You could even just add the new one with a lower prefference number than the other two and leave the others there to fail over onto just incase.

 

Your website person may know but it is likely that your DNS servers are run by your RBC, if you use the whois tool above on your domain you should be able to retrive the technical contact and talk to them directly through those contact details.

Edited June 29, 2010 by SYNACK

[leco]

Did the nslookup thing:

primary name server = int-ns1-wak.rbcname.net

responsible mail addr = webmaster.schoolname.leaname.sch.uk

 

Name server box not in my school, webmaster not in my school. IP address of name server not in my range but is within the grid.

 

So where does that leave me - up thingy creek without the proverbial I suspect. My boss is being very understanding about all of this surprisingly, but I have to get it sorted. We have had three days now without incoming mail, he'll begin to get cross soon.

[PiqueABoo]

primary name server = int-ns1-wak.rbcname.net

 

I would go back to your LEA support and say "I've got a general purpose query about modifying the DNS zone for our school: I'm told I need to make change to that, but the zone seems to be controlled by a server 'int-ns1-wak.rbcname.net and that's not obviously one of my boxes where I can make changes.'.

 

If they say we don't support Exchange, point out that this doesn't involve doing anything to Exchange and it's a 100% DNS issue.

 

webmaster not in my school

 

That's special and it really means: [email protected]

It's an e-mail address anyone can whine at if they have some issue with anything relating to the 'schoolname.leaname.sch.uk' domain.

[leco]

Just fired off an email to someone that I work with, on another IT project, in the LEA. I think the primary name server is one of their boxes since it has an internal address. They also work in IT at the LEA with schools, so should know not only what I'm talking about but also be able to do something about it.

 

Thanks for the info on the webmaster address I did wonder.

[leco]

Update:

It turns out that the firewall rules/filters, between the RBC and the LEA, had not been changed to take into account the school's new server address. So nothing that I had done wrong or not done phew. Email is now flowing back and forth. Thanks for all the help guys.