We are using Amazon Route53 for DNS management at Presslabs. Besides the actual DNS Manager from the Presslabs Dashboard, we also use Amazon Route53 for automatic failover and geo serving of the content.
All sites that are hosted with us have a chain of
Alias DNS Records that are configured together with
Health Checks in order to have a full DNS Failover service.
Practically, this means that whenever a server goes down for any reason, its corresponding health check will fail and Route53 will remove it from the pool of available servers. All these operations are automatic and take about 60 seconds to complete. Other servers are then taking over the traffic and serve your site.