DNS not updated for some

[myjpkl]

I host my dns on fedora, im using WEbmin

I go to Bind DNS, and edit my Master Zone, All address
and modify my mailserver (our mail hoster changed our email server)
previously was mail.xxx.com , 110.x.x.156 change to x.159.

After I changed it, I apply and even stop and start nameserver again...
and even init 6 the server..

Still some of the pc still when i ping mail.xxx.com it returns x.156.
I did a ipconfig /flushdns or client, reboot, renew ip..
Still the same..

What else can do i ?

[flyingfsck]

Your DNS changes may take 4 days to propagate to all other cached DNS servers.

[William Haller]

All DNS changes should be planned in advance. Set your timeouts short in advance so that old cached results expire quickly on all real world and local boxes. The cost for the extra DNS traffic is not large. Make the change. When you have ensured all your changes are working the way you want, reset your timeouts on your bind server to their standard long time. If your mail provider does this often, then just run with shorter times in general. If it doesn't happen often, then see why they didn't give you a heads up.

You can force your local hosts that have the wrong DNS information to flush their DNS entries from the command line - you'll have to query the internet for the proper commands for the various operating systems you have.

ADD: Be sure to flush the DNS information in any active directory servers you have as well. I'd start there and then propagate down to the clients. As far as netbios related browsing is concerned, that can also get cached in a different place but I don't remember where.