A global manufacturing company has offices in multiple countries. They want to interconnect their sites to enable seamless communication and data sharing while ensuring high reliability and security. Which type of network best suits their needs?

A Wide Area Network (WAN) is the appropriate network type for an organization with geographically dispersed sites across multiple countries. By definition, a WAN spans a large geographical area, interconnecting multiple Local Area Networks (LANs) from different locations. This infrastructure is essential for a global company to facilitate seamless communication, share data, and centralize resources. Modern WAN technologies, such as SD-WAN and MPLS, are specifically designed to provide the high reliability and security required for inter-office connectivity over long distances.

B. Metropolitan Area Network (MAN): A MAN is designed to cover a geographic area smaller than a WAN, such as a single city or a large campus, making it unsuitable for a global company.
C. Personal Area Network (PAN): A PAN is a very small-scale network used for connecting personal devices (e.g., via Bluetooth) and is not applicable for interconnecting corporate offices.
D. Local Area Network (LAN): A LAN is confined to a limited area like a single office building. While each office would have its own LAN, a WAN is required to connect these individual LANs.

1. Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. In Chapter 1, Section 1.3, "The Network Core," the text distinguishes network types by scale, defining a WAN as a network that spans a large geographical area, such as a country or continent.

2. Stallings, W. (2017). Data and Computer Communications (10th ed.). Pearson. Chapter 1, Section 1.4, "Wide Area Networks," explicitly states that WANs provide long-distance transmission of data and are used to connect geographically distributed sites, which directly matches the scenario.

3. Tanenbaum, A. S., & Wetherall, D. J. (2011). Computer Networks (5th ed.). Prentice Hall. In Section 1.2.3, "Wide Area Networks," the authors describe a WAN as a network that "spans a large geographical area, often a country or continent," and is used to connect machines that could be "many thousands of kilometers apart."