I have a public server running Rocky Linux 8, with a single eth0 network interface.
The provider gave me a failover IP which points to that server, but I have a hard time to figure out how to configure it.
Ideally, the server should be reachable by two public IP addresses (the one assigned by default as well as the failover IP). Is there any reliable documentation on the subject ? I’ve waded through a dozen blog articles on the subject, but nothing worked so far.
It’s not failure-related, but it’s complicated. The company “manages” (so to speak) its DNS via Ionos.fr. I tried to add an A record for the new server in their horrible GUI interface, but to no avail. Turns out the last admin who worked in the company set up his own DNS configuration with Cloudflare, thus bypassing the DNS handling by Ionos. And nobody dares to touch it (they have a few other websites on various domains and subdomains). Me, I’m just handling their OwnCloud installation.
So in short, it’s impossible for me to simply add an A record pointing to the new server. On the other hand, I can use the old server’s failover IP and migrate it over to the new machine. So the stale DNS record points to the new server instead of the old one.
That most likely means that the nameservers for the domain managed at Ionos (for renewals), has the domain pointed to use Cloudflare servers and therefore DNS entries are active there. That is easy enough to resolve, you just simply log into Ionos panel and ensure that the nameservers in use for the particular domain are restored to use Ionos servers instead.
However, you will need to ensure that all existing entries that are working via the Cloudflare servers are also created on the Ionos servers before you switch back.
I use Cloudflare for all the domains purchased by the company I work for. When they purchase a domain at a Polish DNS company, we just then simply change the nameservers from using the company where they were purchased, to the Cloudflare ones. When we no longer wish to use let’s say Cloudflare or whoever, we just point them back to the namservers of the company where we purchased them.
In effectively at present, you are only using Ionos currently for renewal of the domain, rather than their nameservers but you can change that and get full control of it again.