Question: Today, computer security comprises mainly "preventive" measures, like firewalls or an exit procedure. A firewall can be defined as a way of filtering network data between a host or a network and another network, such as the Internet, and can be implemented as software running on the machine, hooking into the network stack (or, in the case of most UNIX-based operating systems such as Linux, built into the operating system kernel) to provide real time filtering and blocking. Another implementation is a so-called physical firewall which consists of a separate machine filtering network traffic. Firewalls are common amongst machines that are permanently connected to the Internet.
Is there an answer to this question: What does a physical firewall consist of?

Answer: a separate machine filtering network traffic

Question: A significant and far-reaching shift in human subsistence and lifestyle was to be brought about in areas where crop farming and cultivation were first developed: the previous reliance on an essentially nomadic hunter-gatherer subsistence technique or pastoral transhumance was at first supplemented, and then increasingly replaced by, a reliance upon the foods produced from cultivated lands. These developments are also believed to have greatly encouraged the growth of settlements, since it may be supposed that the increased need to spend more time and labor in tending crop fields required more localized dwellings. This trend would continue into the Bronze Age, eventually giving rise to permanently settled farming towns, and later cities and states whose larger populations could be sustained by the increased productivity from cultivated lands.
Is there an answer to this question: What trend led to a major shift in the livelihoods of early cultures?

Answer: crop farming and cultivation

Question: In 1962, the Supreme Court addressed the issue of officially-sponsored prayer or religious recitations in public schools. In Engel v. Vitale, 370 U.S. 421 (1962), the Court, by a vote of 6-1, determined it unconstitutional for state officials to compose an official school prayer and require its recitation in public schools, even when the prayer is non-denominational and students may excuse themselves from participation. (The prayer required by the New York State Board of Regents prior to the Court's decision consisted of: "Almighty God, we acknowledge our dependence upon Thee, and we beg Thy blessings upon us, our parents, our teachers, and our country. Amen.") As the Court stated:
Is there an answer to this question: Even if a prayer is non-denominational it's still considered what?

Answer: unconstitutional

Question: The top 50 m (160 ft) of a glacier are rigid because they are under low pressure. This upper section is known as the fracture zone and moves mostly as a single unit over the plastically flowing lower section. When a glacier moves through irregular terrain, cracks called crevasses develop in the fracture zone. Crevasses form due to differences in glacier velocity. If two rigid sections of a glacier move at different speeds and directions, shear forces cause them to break apart, opening a crevasse. Crevasses are seldom more than 46 m (150 ft) deep but in some cases can be 300 m (1,000 ft) or even deeper. Beneath this point, the plasticity of the ice is too great for cracks to form. Intersecting crevasses can create isolated peaks in the ice, called seracs.
Is there an answer to this question: What is the free flowing upper section known as?

Answer:
unanswerable