A. Explain why two NSs is the minimum number you would ever want to run in an organization's networked IP environment. Consider the following factors, which can influence the total number of NSs present on a typical organization's internetwork:

• If an NS is available directly on each network or subnet in a local internetwork, routers need not become potential points of failure. Consider also that multihomed hosts make ideal locations for DNS because they can directly service all the subnets to which they're connected.
• In an environment in which diskless nodes or network computers depend on a server for network and file access, installing an NS on that particular server at a minimum makes DNS directly available to all such machines.
• Where large time-sharing machines—such as mainframes, terminal servers, or clustered computers—operate, a nearby DNS server can offload name services from the big machine, yet still provide reasonable response time and service.
• Running an additional NS at an off-site location—logically, at the site of the ISP from which your organization obtains an Internet connection—keeps DNS data available even if your Internet link goes down or local NSs are unavailable. A remote secondary NS provides the ultimate form of backup and helps ensure DNS reliability.
b. Given the foregoing information and the fact that the organization operates three subnets at each of its Indiana locations along with a large clustered terminal server at each location, explain how XYZ might want to operate as many as nine NSs for its network environment.