How to make a backup IP for a domain?

Question

Domain Name System

Good afternoon, there is a domain on which you need to organize automatic switching to another IP, if the first one is unavailable, is it possible to implement this?

Answer 1

Because DNS has a cache on devices (DNS servers of providers, routers, computers), and if you specify a TTL of 1 hour, you can get a real cache lifetime of much more than 1 hour - it is not advisable to do this using DNS tools. (Why a backup that turns on up to 3 hours?)
It's much easier to use sharedip, or dynamic routing, if the network is under your control.
If you live on hosting, then the way out with a normal and fast working reservation is to use a third-party (alien already reserved by means of the ip network) in the "client->magicip->your servers" scheme
If you want to implement this using DNS tools, despite long downtimes, you need to write a script that monitors addresses for "alive or dead", changes the zone file, SOA and reloads bind. In this case, it is better to have a minimum TTL for switching records, but this will lead to slowdowns for users (both desktop and mobile) and will not solve the problem of downtime when switching root.

Answer 2

Depending on the data and what you do on it.
For example, you can specify two A records.
Then the domain will, in principle, give out one IP then another.
Or if this is a web server, then Give A the nginx proxy entry that will already change the backends depending on the performance of nginx.org/en/docs/http/load_balancing.html
what service you have hanging there, describe in more detail