Log in as an administrator with permission to change the configuration.
Change to the /etc/opt/SUNWics5/cal/config directory.
Save your old ics.conf file by copying and renaming it.
Edit the following parameter as shown in the following table:
If "yes", when HTTP access is allowed, checks the client IP address against DNS. The default is “no”.
Save the file as ics.conf.
Restart Calendar Server.