Database synchronization is to establish data consistency between two or more databases, automatically copying changes back and forth. This is to ensure application can failover to the Disaster Site with the same data available.
DNS Failover & Load Balancing
DNS Failover is a technology mechanism that automatically updates DNS records if something goes wrong with a DNS name server on the network. Disaster scenarios almost always strike unexpectedly. In a DR event, your traffic will automatically be diverted to the fastest and healthiest resource available.