[horde] FDQD error

[Andrew U. Frank]

when installing a new horde server, there are problems with the
qualificaton of the server name (at least on Ubuntu installation) and
the error FDQD required or do not use cookies.... is raised.

i have avoided this by changing by hand the horde/config/conf.php file 
to change the cookie domain value to "mynode.mydomain.com"

this works, but seems not the right solution. where is the value for 
SERVER_NAME set?

thank you
andrew