DMZs are firewall setups where not only the Web server is protected from unhindered access from the public internet, but the corporate network is also protected from the Web server. Basically, the Web server is placed on a network segment which is protected by firewalls both externally (network traffic going to and from the public internet) and internally (network traffic going to and from the internal, corporate network).

The challenge of DMZ setups is that the Web application server residing in the DMZ is seperated by a firewall from the database server residing on the internal, corporate network.

Using the iSeries as the backend database server requires installation of the Plex dispatcher YOBSYTDPDP in order communicate through a firewall.