Regarding my last question. I know now, that problem lies in slow DNS resolution. What can cause that, if user says that he has problems only with that one particular domain.
Weird thing is that user has no problem with another domain on same DNS server, redirecting to same IP as
And btw. shouldn't be domain somehow cached on user end? Because he has all the time problem with slow loading. I told him do flush DNS cache in Windows, but that doesn't helped.
Unfortunately I can't debug DNS server, because we are using our domain registrar DNS servers.