DE ♦ EN (Theano GmbH)  » Security  » Failover Setup

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Reliability, Failover

The IBAN calculator is hosted at several Hetzner computer centers in Germany and Finland. Our hoster promises a network availability of 99 %. We alleviate the consequences of hard drive failures by using a RAID-1 setup in every server.

To surpass the 99% availability rate, we use an automatic DNS-based failover mechanism.

If or becomes unavailable, its DNS entry (with a TTL of 1 minute) is automatically pointed to another load balancer out of the pool. We have load balancers in different computer centers, thus it is unlikely for them to fail at the same time.

The name servers and the monitoring service which initiates failovers are all located outside the computer centers which host our IBAN servers. This means that the failover mechanism runs independently of the servers whose failures it deals with.

Required Firewall Configuration

If you use a firewall, please open it for the following IP addresses to make sure you actually benefit from our automatic failover mechanism:


You may also use IPv6 for reaching the servers above. The DNS-based failover for and works for both the A records (IPv4) and the AAAA records (IPv6) for those server names. If you want to use IPv6, please open your firewall for:

  • 2a01:4f8:231:4b91::bac2
  • 2a01:4f9:4a:2ec8::6483
  • 2a01:4f9:4a:2ec8::6ab2
  • 2a01:4f8:171:2695::41