Mixture - thanks for a massively unhelpful post.
Yes, I know the DNS doesn't assign the IP - but you understand the concept of "dumbing down" to explain a complex subject?
I could have gone on about IPV4, IPV6, SOA,TTL, NAT etc - but that would have confused everybody. So instead, I wrote an easy to understand post.
But my point was correct. The DNS switching sites work! And that was the sort of hell the OP was asking for!
OD