We switched shared hosts from a local mom and pop to crystaltech. The site was all copied over and ready for the DNS change. The mom and pop site offered no tools to manage DNS ourselves, so we had to make a phone call and time the final move of the database with their changing of the DNS.
What happened From Oregon on Comcast, and the old host in Oregon on a regional fiber provider. The old host updated their DNS servers to point at our new IP address. They changed it from 207.x.x.x to 67.x.x.x
In Oregon, I flushed my DNS on my windows 7 machine on two computers and in less than 30 seconds the domain name site.com was working as expected. Ping tracert confirmed the domain name was resolving to the new IP at the new host.
In Florida, the client was reporting the domain name was resolving to the old site. (We put up "we're moving" pages on the old host server.) Her mac pinged the domain name and it resolved to the old host. We rebooted, then flushed the DNS in the terminal. 6 hours later her computer still cannot resolved to the new IP address.
One machine in the office in FL can access the new site correctly. Other machines in the South FL area cannot access the site. A call to the AT&T tech confirmed that ping and tracert from his area (same network) were resolving properly.
What the heck is wrong?
Why doesn't my client's mac use the nameservers to get the IP address? The IP address is different and only the nameserver on record knows it.
Is it AT&T? Is it OSX? Is it the old host DNS? Is it the new host DNS? Is it because the old host's TTL on their DNS server was 72 hours?
I have since changed the name servers with the domain registrar, so in a couple of days this will all be over, but I still curious what the heck happened.