DNS Failover / High Availability – ben.goodacre.name/tech
The native Linux resolver with default settings cannot be relied upon for HA / failover. By default there are two attempts each with a 5 second timeout. Therefore every query has to wait 10 seconds before the secondary DNS server is queried. Linux does not
natively mark a DNS node is ‘dead’ and send all queries to a secondary node, it try the primary upon every single query.