cPanel DNS Only Failover

[taenkarth]

I have a big issue that I just have not found a good way to accomplish without a lot of manual work.

Here is the scenario:

1. I have 2 cPanel Web servers at one location on a single Class C subnet.
2. I have a replica of those servers off site on a seperate Class C subnet.
3. I have two DNS servers (want to migrate to cPanel DNS Only) that are in control of all of the records for all of the domains hosted on the above two servers.
4. All servers are virtualized in a VMware ESX 4 environment.
5. I am using Double-Take to replicate VM to VM from each site.

When failover happens how can I get DNS to point to the addresses on the other subnet?

Keep two things in mind.
1. DNS Round robin will not work as the off-site servers are offline until needed for failover.
2. Cannot use a load balancer on the main site as the DR scenario is for loss of site 1 connectivity which would render a load balancer unreachable.

What are my options?

[cPanelMattCurry]

Hello,

I do apologize that you are having issues, unfortunately this would be something that we could not support directly. I would recommend speaking with your Data Center on this issue. It may require a special setup; please let us know if you have any other questions.

Thank you,
Matthew Curry

[UNIXy]

When failover happens how can I get DNS to point to the addresses on the other subnet?

Keep two things in mind.
1. DNS Round robin will not work as the off-site servers are offline until needed for failover.
2. Cannot use a load balancer on the main site as the DR scenario is for loss of site 1 connectivity which would render a load balancer unreachable.

What are my options?

I believe the technology you're after is called Dynamic DNS Updates. It's fully documented in RFC 2136. Essentially, your monitoring server / tools can be authorized to update the A record of your domain when they detect that the current IP in the record is not responding to queries. In this case, it will tell your DNS server to update the A record with the other subnet's.

Here's some reading that can get you started:

RFC 2136: RFC 2136 - Dynamic Updates in the Domain Name System (DNS UPDATE)
Dynamic DNS: Dynamic DNS - Wikipedia, the free encyclopedia

Let me know if you have any question.

Best