Reciprocal agreements can be effective solutions to disasters of limited duration and magnitude, especially for smaller organizations. Major disasters, however, such as the September 11, 2001 destruction of the World Trade Center, are likely to affect both parties to the agreement. Another problem is that the "host" organization must use its information system resources, too. Consequently, many organizations use more elaborate and expensive methods of arranging for access to alternative information systems infrastructure. One solution involves purchasing or leasing a cold site, which is an empty building that is prewires for necessary telephone and Internet access, plus a contract with one or more vendors to provide all necessary computer and other office equipment within a specified period of time. Note that a cold site still leaves the organization without the use of its information system for a period of time. A more expensive solution for organizations, such as financial institutions and airlines, which cannot survive any appreciable time period without access to their information system, is to create what is referred to as a hot site. A hot site is a facility that is not only prewired for telephone and Internet access but also contains all the computing and office equipment the organization needs to perform its essential business activities. Thus, a hot site is essentially a backup infrastructure designed to provide fault tolerance in the event of major disasters.