Hi Robert,
Hmmm... seems it must be doing it's own DNS setup/entry on the non-OS/2 side. Is there an entry in the Windows hosts file? Or what happens, when successfully connected in Windows, if you open a command prompt and type "ping event.vodafone.de"?
Windows DNS has always been broken in its implementation, especially in as far as hiding setup mistakes, nothing new there, a bit like IE, ie, it works fine in IE but doesn't in Netscape/Firefox etc so the company concerned reassures everyone there is no problem :-)
From OS/2 (Same from AIX) using Bind v9.7.2 host.exe etc
[H:\]ping event.vodafone.de
ping: unknown host event.vodafone.de
From WindowsXP SP3, event.vodafone.de = 151.189.21.148
There is no problem, it works fine

Cheers