How to set A Records and MX records correctly [closed]

Question

I just wanted to confirm something if that's okay? :) I am setting up a new site for someone and they already have email configured on an existing server and want the website on a different one. They have already set the www a record to the new server IP and this works fine and they have two MX records setup and the email is working fine. They have not updated the @ A Record, this is still pointing to the mail server IP (which means the non www version of the site goes there instead). Am i not right in thinking that if you have the MX records set then the A Records for both www and @ can be set to a different server IP and will have no impact on the email (as this will be controlled purely by the MX records)? So I can change the @ a record to the new server ip as well and this won't affect their email right? Assuming this is okay will it screw up the RDNS or any of the other email validation techniques?

Thanks so much for your help as ever,

Dave

Answer 1

You should be fine changing the root record. Whenever an email comes in it will always look at the MX records. There are two things to check though.

The MX records will point to a domain name, are they pointed at the root domain? Secondly do they use any form of webmail? You might need to create another record such as mail.example.com in order to ensure that they can still access these two things.

Most sender validation uses different DNS entries and doesn't rely on the A records in any way so you should be fine changing things.

Answer 2

Also helpful:

nslookup -type=MX yourdomain.com
dig MX yourdomain.com

Answer 3

Correct. A and MX records are not related to each other and will therefore not have an impact on each other. You can point them to different domains.

• A record: host address (typically the IP of the website domain)
• MX record: mail exchange (the web server which is handling your e-mail -> which can be on a completly different server)

Answer 4

Should be just fine to change the A records and leaving the MX records intact.

For example, I have a website hosted on a server and I have Google Apps for email. All I did was insert the MX records into my hosting provider and my emails went through no problem.