Explanation/Reference:
Section: Addressing and Routing Protocols in an Existing Network Explanation Explanation:
External Border Gateway Protocol (eBGP) would be the most appropriate routing protocol for a router that has redundant links to a router within a different autonomous system (AS). An AS is defined as the collection of all areas that are managed by a single organization. Routing protocols that dynamically share routing information within an AS are called interior gateway protocols (IGPs), and routing protocols that dynamically share routing information between multiple ASes are called exterior gateway protocols (EGPs). Border Gateway Protocol (BGP) routers within the same AS communicate by using internal BGP (iBGP), and BGP routers in different ASes communicate by using eBGP. BGP is typically used to exchange routing information between ASes, between a company and an Internet service provider (ISP), or between ISPs.
Static routing, not BGP, would be the most appropriate routing method for a router that has a single link to a router within a different AS. Because BGP can be complicated to configure and can use large amounts of processor and memory resources, static routing is recommended if dynamic routing information does not need to be exchanged between routers that reside in different ASes. For example, if you connect a router to the Internet through a single ISP, it is not necessary for the router to run BGP, because the router will use a single, static default route to the ISP for all traffic that is not destined to the internal network.
An IGP would be the most appropriate routing protocol for a router that has a single link or redundant links to a router within the same AS. Enhanced Interior Gateway Routing Protocol (EIGRP), Open Shortest Path First (OSPF), and Routing Information Protocol (RIP) are examples of IGPs.
Reference:
CCDA 200-310 Official Cert Guide, Chapter 11, BGP Neighbors, pp. 444-446 Cisco: Sample Configuration for iBGP and eBGP With or Without a Loopback Address: Introduction