I had a client saying he can't reach his site with www in front of his domain. But I can access his site both with or without www.
Anyone know the possible reason why he can't reach his site with www.

Did you recently add his domain to your DNS?

It's probably DNS, like archangel is hinting at.

If that person tried to get to their site at www.theirdomain.com before the DNS changes were added, then their machine is going to do a negative cache. Which means that it will actually cache a negative value until the cache expires.

You could go there, because you hadn't tried it before there was a DNS entry.

Most workstations will free up their negative cache upon reboot. Otherwise, it really depends on how your DNS server is set up and your client's DNS servers are set up on how long the negative cache will last.

Of course it could be a million other things, but that's the most likely answer, I think.

Hi!
A simple thought. Are you able to ping to
www.domain.com.
If yes does
ping www.domain.com and
ping domain.com point to the same IP.
If no only then there is a DNS problem.

Have a great day :)

Regards
Amar