looking for advice/best practice on dns config

[lemmy]

Hello,

We are currently using Veeam in a replication capacity only. A handful of our mission critical VMs are replicated to a offsite standby ESXI server where they can turned on in case of a DR situation.

I'm looking for advice or documents on how to properly configure our DNS entries. We've tried running a test server with two (2) DNS entries but are getting pretty wacky results.

example : testserver.domain.com has 2 entries,
10.10.10.10 current "live" IP
10.10.20.10 to be used in case of DR

We've set a low TTL (1 min).

what we are trying to achieve is that if we flip over to the failover server, that it represent as little impact to the end user.

Right now, with dual entries, depending on when we do a nslookup, the secondary server returns even if it is powered off. I was under the impression that only the live server would resolve.

any ideas? what are we doing wrong?

[nefes]

Could you please elaborate a little, why you want to use Re-IP on your replicas?
If you will leave testserver.domain.com with it's "live" IP it will be resolved no matter where is it up.

[JosueM]

Since your DR site is another network segment, I believe this is not a DNS issue but a routing topic. We are in asimilar situation but still haven't figured it out how to properly handle.

[hans_lenze]

First: This solution is only valid if you're using a Windows DNS server with dynamic updating enabled and use a domain joined server. More information on dynamic updating: http://technet.microsoft.com/en-us/libr ... 71255.aspx
For security reasons, it is a bad idea to use any other than secure dynamic update. http://technet.microsoft.com/en-us/libr ... 53751.aspx

You could have a single DNS record pointing to your live server and have that record changed automatically when the DR site comes online. During the boot proces the Windows server will automatically update its own DNS record so it resolves to the correct IP address. For this to work, you'd have to have a functional DNS infrastructure at the DR site that is also available to the clients.

If you set multiple DNS records for the same name, most DNS servers will start to switch the order in which the records are returned to a query. Meaning you'll get a round robin of the existing records. This is not what you're looking for.