Thursday, 21 June 2007

eMail

One of the most important things do with email is MX records, I’m surprised with how often these are over looked, and MX record can be a IP address but most common is for it to be a A name record an A name record also know as a host record is simply a host ie a computer name to an IP address.

When a query is done most MX records respond with something like this you can have many MX records, the email will way contact the one with the lowest number first and then work its way up.

MX preference = 20, mail exchanger = secondary.mail.com
MX preference = 10, mail exchanger = primary.mail.com

And the A name query looks like this

Name: primary.mail.com Address: 205.158.62.116

Now because there is traffic routing and other many factors that we cannot control sometime the mail will go to the second MX or high if you have one because it can get to the first, so it’s as important to make sure these mail server accept the messages and much as the primary on does, otherwise you end up with missing email or failure with message deliveries.

You must create at least two independent mail servers on more than one site using your ISP is often the easiest way.
And also make sure all of your server listed in the MX records respond to the domains you have.

Tuesday, 5 June 2007

Windows 2003 R2 DHCP Error

Seems to be a bug in the setup where the windows firewall is on still after you have run the setup, this blocks the DNS and the DHCP also File and Print sharing in not enable as an exception, a quick fix to this is to create and exception for the BOOTP and DNS server.

Goto the control panel and open the Windows Firewall and on the Exceptions tab click the add port, you’ll need to do this for both UDP port 53 and UDP port 67 then make sure they are ticked and any others you might need like File and Print Sharing.

This bug also comes up on SBS 2003, I recommend rerunning the SBS wizard.