What security concept encourages adminstrators to install firewalls, malware scanners, and an IDS on every host

Acolor class has three public, integer-returning accessor methods: getred, getgreen, and getblue, and three protected, void-returning mutator methods: setred, setgreen, setblue, each of which accepts an integer parameter and assigns it to the corresponding color component. the class, alphachannelcolor-- a subclass of color-- has an integer instance variable, alpha, containing the alpha channel value, representing the degree of transparency of the color. alphachannelcolor also has a method named dissolve (void-returning, and no parameters), that causes the color to fade a bit. it does this by incrementing (by 1) all three color components (using the above accessor and mutator methods) as well as the alpha component value. write the dissolve method.