An organization has a number of Local Area Networks (LANs) linked to form a single Wide Area Network (WAN). Which of the following would BEST ensure network continuity?

For a Wide Area Network (WAN) connecting multiple LANs, permanent alternative routing is the best method to ensure network continuity. This involves designing the network with redundant paths and using dynamic routing protocols (e.g., OSPF, BGP). If a primary link or router fails, traffic is automatically rerouted through a secondary path with minimal or no disruption. This proactive approach provides high availability and fault tolerance, which are essential for maintaining continuous network operations.

A: A third-party repair contract is a reactive recovery measure, not a proactive method for ensuring uninterrupted service continuity. B: Pre-built servers and routers are part of a disaster recovery plan for replacement, but they do not prevent initial downtime. D: Full off-site backup is critical for data recovery and business continuity but does not ensure network connectivity or continuity.

1. Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. Chapter 5, "The Network Layer: Control Plane," explains how dynamic routing protocols provide alternative paths to maintain connectivity when network topology changes.

2. National Institute of Standards and Technology (NIST). (2010). Special Publication 800-34 Rev. 1: Contingency Planning Guide for Federal Information Systems. Section 3.4.2, "Continuity of Operations," discusses the need for alternate communication capabilities and redundant network links.