How Long Does a High-Defense Line Switch Take Effect: DNS Changes Take Minutes to Hours, BGP Steering Takes Seconds, and Always-On Access Requires No

The time it takes for a high-defense switch to take effect depends on how traffic is steered to the high-defense network. DNS changes are affected by TTL and local LocalDNS caches, typically taking a few minutes to tens of minutes, and in some cases hours. BGP route steering generally takes a few seconds to 60 seconds. When the business is already on the high-defense link, adjusting policies only takes seconds. This article covers two scenarios—planned cutover and active attack—and provides the operational sequence to shorten the wait and methods to confirm whether the switch has taken effect.