Barry,
thank you for the information. We've found the problem and it was a
network problem.
I got fooled by a firewall in the following way:

Our default router in the LAN must be addressed to reach the MVS Host.
So I tried to ping our ADSMHOST to get sure that the symbolic name is
correctly resolved. And by pinging the route to the host is available.
Not correct in our case: During installation the IP-Address of the
firewall got typed into the field for the default router. My ping was
accepted by the firewall, the address was known as internal, got routed
to the default gateway and I had just one more hop to the host. The
return package then got routed without firewall and this direct route
got cached on the client.
Immediately after the ping ADSM worked perfectly, as it used the cached
route.
But after expiration of the cached route entry, the firewall blocked the
connection for ADSM's default port.

Regards,
Michael
--
Michael H. Bartl, ADAC e.V. (IDL/PPO)
Michael H. Bartl, ADAC e.V. (IDL/PPO)
Tel.: (089) 7676-4063, Fax: (089) 7676-8161
EMail: Michael.Bartl AT Zentrale.ADAC DOT de

>----------
>Von:   Barry Fruchtman[SMTP:bf AT VNET.IBM DOT COM]
>Gesendet:      Donnerstag, 3. Juli 1997 17:47
>An:    ADSM-L AT VM.MARIST DOT EDU
>Betreff:       ANS4017E on NT-Server
>
>  ADSM does not find routes to the server. ADSM uses
>standard WinSock calls and basically just
>asks for a session with the server by name
>or address ( whichever is provided in the options file ).
>If the connection is failing beyond that point, you've
>got a problem with the network or your TCP/IP configuration.
>ADSM does not contain routing software.
>
>Barry Fruchtman
>ADSM Development
>