When a DNS finally changes, will it temp change back to the old name servers?

Ok this might sound like a really stupid question, but I heard conflicting answers. Finally the DNS changed from my old host to my new host. My old host I replaced the index file with a "maintenance" page and the new server has the normal content. Everyone says the site looks fine but I heard rumors that when the DNS changes sometimes people can still view the content off the old name servers.

Is this correct? or once it is flipped it is a global static change?

I thought this was the best place to ask this question and I did google first.
thanks for your time

 

The old page (old nameservers) can be accessed some time due to the DNS propagation. The DNS cache which is stored in the users system, may sometime lead them to the old site (rarely). Once the DNS cache is cleared (usually 24-72hrs) users will be able to access the new one.
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i guess after 72 hrs all cache is cleared

 

I agree. Some times people don't understand DNS propagation, and assume that there's problems. But no, its as they said above, sometimes, and very rarely, the old nameservers can be accessed.