I rather thought DNS chugs along because it does not have to handle the same amount of changes that BGP does? Ok, the churn problem is harder ifyou try push, but people expect to be able to make route changes inseconds, ms being talked about as a target; I rather think to change myDNS entry takes a little longer.
The problem isn't changing the entry on your server, but the delay caused by the caching. In a push model, the entity doing the pushing knows when a new push is required. In a pull model, the entities doing the pulling have no idea when would be a good idea to execute a new pull.
However, I think it would be possible to come up with a fairly light- weight way to push out notifications that a new pull is in order. And if the decapsulating devices get to see the addresses of the encapsulating devices, they can easily signal back that there was a change of some sort. Or say the same thing implicitly by becoming quiet.
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