IP MX Record - A Record Change 1

[wkim623]

A question for you all.

My current configuration for email is working but we want to change over to a new fibre connection. Unfortunately our current public IP address will not be the same as we got the new service from a different provider.

Here is my dilemna, since I have new public IP address when I do the cutover to the new ISP. We will have to redirect the A record to the new IP address. Unfortunate part we can't lose email capability to receive and send. As we know it takes time for the new record to propogate. Does anyone know another way to avoid losing the service without doing this scenario.. I was thinking.

Scenario was to create another MX record and A record to point to the new IP. Give the MX preference at 20 while the other connection is online. Then decomission the old connection so that all email will be sent to the new one. Once it is ready.

I don't like doing it this way but this looks to be the best solution for me cost wise.

Any help or input is appreciated. Thanks!

 

[jfp23]

Is your business 24/7 critical? I have found do the cutover after close of business on a Friday and your gap will be minimal.

 

[wkim623]

No they aren't 24/7 but the business units say it's critical to have no down time of 24 hours. With that said, normally we all know it doesn't take 24 hours, but I can't give them a firm a time as no guarantee is given by anyone for these changes.

Let me give you the reason why it is critical right now. Right now our company is on the verge of exploding growth wise. We are about to open a new production plant in 2 weeks...along with that our company is hammering out contracts and deals to sell our projected production output. So a lot of deals are happening now as our production plant is about to open. So any amount of downtime right now is not ideal.

 

[58sniper]

MX records don't propagate. But they do have a TTL (time to live) parameter.

Once the new connection is working, create a secondary MX record for your new connection, with a cost of 20.

Wait at least one TTL period (typically 24 hours), and then update the current MX record (since that's likely the one your SSL certificate is named for).

No mail lost. No downtime.

Pat Richard
Microsoft Exchange MVP
Contributing author The Complete Reference: Microsoft Exchange Server 2007

 

[wkim623]

58Sniper,

Ok so what I was thinking is the best way. Just some clarification though.

I don't have to create a new A Record for the 2nd MX record? I can use the same A record that I'm currently using?

I guess this question would probably be answered by the previous question..but when you mean update the MX Record if I'm understanding your post is to remove this record after the TTL has been done?

I was also curious if creating the 2nd MX Record for load balancing..in theory would this work as the previous suggestion of making the preference 20?

Meaning - make both MX Records have the preference value of 10.

Thanks for replying and I totally forgot about the SSL. Thanks for reminding me!

 

[58sniper]

A minor typo in my original reply.

Create the A record for the new connection. Once you're sure that lookups for it are working, set it as an MX record, with a cost of 5. Wait at least one TTL period, and then kill off the old one.

If you make two MX records, both with the same cost, then you'll likely cause round robin DNS. That's somewhat load balancing, but not quite. It does load balance the lookups, but not the traffic. An example:

sending server A does a lookup, and gets mail1.domain.com. It connects to that resource, and sends a 50kb message.

sending server B does a lookup, and gets mail2.domain.com. It connects to that resource, and sends you 20 messages, each 10MB.

The lookups are balanced, but what each sending server is transmitting isn't. Does that make sense?

Pat Richard
Microsoft Exchange MVP
Contributing author The Complete Reference: Microsoft Exchange Server 2007