Originally Posted by kong121s
thank for your help, falko
but I can ping test.com now!
may be ISP doesn't fully update.
I think that coz' I did't change anything at last night
but it work at this morning.
Most ISP's DNS resolvers will cache DNS answers for 4 hours (on average) to save them work. Windows does this too, except it remembers entries for 24 hours (by default) and even caches failed DNS answers for five minutes.
It's almost essential to have a local non-caching (or the ability to clear the cache) DNS resolver when running a DNS server. Otherwise you can use (at the windows command prompt)
nslookup <name to lookup> <ip of dns server to use>
to see if it's your ISP's DNS server or your DNS server.
Also you can flush windows cache with