The problem I deal with is that Although my friend has changed DNS and registered the new name of his site ... he sees the old DNS. His site now is on my server (DNS). I ping from different location and I "see" my DNS correctly. He said that the DNS change had been made two months ago!
When he pings he sees his old (on his ISP server) DNS.
Should he add (advanced TCP/IP settings/DNS/WINS) my DNS IP in his configuration ??? (Windows 2000)
Would that make his pinging see my (correct) DNS IP? Despite the fact that his ISP had the old DNS?
well, first you have a laps of time when the information is in caches.
Depending on the setting in Bind, it can take 24h-48h before he see the new IP.
You can ask him to do: "ipconfig /flushdns" to flush the dns cache to see if this will fix the problem.
EDIT: I see the 2 months ago after, sorry.
The problem can be the ISP. I know some ISP caching DNS result and keeping it for month, I already see some request on my old server for my domain 2-3 months after the change...