DNS Query

[RSi Dave]

At work I recently migrated exchange from 2000 to 2007 and everything is working however we are also changing ISP so we will be getting a new IP address. Now currently we have our MX records setup like:

0 new-servername.domain.com
1 mail.domain.com
2 old-servername.domain.com

reason we still have old-server.domain.com is because the reverse DNS points here.

Now i am just wondering do we need more than 1 mx record for a single domain enterprise?

Could i get away with just having mail.domain.com? I would like to get this sorted so we can tell our ISP the correct reverse DNS...

Also how do A records work e.g. we currently have an ftp.domain.com which points to our IP address which when it comes in gets filtered through the firewall on the relevent port to the ftp server. Now we would like to use exchange OWA and activesync and currently use https://new-server.domain.com/site however is this correct? Should we just use mail.domain.com or have an A record which goes to owa.domain.com????

Any help appreicated. And sorry if these appear to be silly stupid questions

 

[Longy]

I normally set up:

5 mail.domain.co.uk
10 mail.ispbackup.co.uk

PTR set up for domain.co.uk on you wan connection for exchange.

mail.domain.co.uk/exchange for OWA

 

[Longy]

does ftp.domain.com not cause problems when u need to ftp to your domain? unless it's the same server?

 

[DMS]

No domain requires more than one MX record to receive email. You can set up MX records for child (sub) domains if need be but you don't need to for the root of your domain.
On the other hand, you can have as many MX records as you like.
When an MX record is looked up for your domain by the server relaying an email message, it will automatically send it to the address with the highest priority (lowest number). Additional MX records are basically for failover (or load balancing depending on how they're configured). So if the server with your record for mail.domain.co.uk with priority 1 doesn't respond, it will try to relay to the next lowest numbered host and so on.

To me it sounds like you need to make sure you've got an A record configured pointing mail.domain.co.uk to the public IP address of your mail server.
Then your highest priority MX record (the one with the lowest number) needs setting to mail.domain.co.uk.
You can set up an A record for ftp.domain.co.uk pointing to the same IP address as well. It doesn't matter. All an A record does is point a host name to an IP address. As long as it can be resolved, clients will be able to communicate with any services that are accessible on the server with that IP address.
Then of course you've got a PTR record which is set on your ISP's nameservers that will facilitate a reverse DNS lookup. The PTR record should be set to mail.domain.co.uk for best results.

 

[RSi Dave]

We have A records for all of the above and ftp.domain.com pointing to our IP address.

ftp.domain.com seems to know that it wants to connect over ftp and the firewall routes traffic to the correct server.

Any best practice on the numbering. for example we currently use 0, 1, 2 but longy is using 5, 10 ?

I will make sure we use mail.domain.com for all our connections and get the reverese DNS setup with that too.

Thanks for you help guys

 

[DMS]

The only best practice numbering-wise is to use them as intended - to prioritise which server(s) your mail gets delivered to.
The lower the number, the higher the preference. The highest preference has to be tried first before the sending mail server can try the next highest.
If multiple MX records have the same preference, they will all be tried before moving onto the next highest preference.
It doesn't matter if you use 1,2,3,4,5 etc, or 5,10,15,20,25 etc... but it's good practice to leave a few priority numbers available between each 2 MX records in case you want to introduce additional mail servers in future.

 

[RSi Dave]

cheers darren, much appreciated on clearing things up

 

[DMS]

No worries.