CompTIA Network+ Question B-7

A company wants to create highly available datacenters. Which of the following will allow the company to continue to maintain an Internet presence at all sites in the event that a WAN circuit at one site goes down?

A. Load balancer

Correct Answer: D

A collection of networks that fall within the same administrative domain is called an autonomous system (AS). In this question, each datacenter will be an autonomous system.
The routers within an AS use an interior gateway protocol, such as the Routing Information Protocol (RIP) or the Open Shortest Path First (OSPF) protocol, to exchange routing information among themselves. At the edges of an AS are routers that communicate with the other AS’s on the Internet, using an exterior gateway protocol such as the Border Gateway Protocol (BGP).
If a WAN link goes down, BGP will route data through another WAN link if redundant WAN links are available.