A routing protocol is a set of rules that determines how routers exchange routing information and select the best paths to reach different destinations on a network12.
There are different types of routing protocols, such as interior gateway protocols (IGPs) and exterior gateway protocols (EGPs)12.
IGPs are used to exchange routing information within an autonomous system (AS), which is a group of routers under the same administrative control or authority12.
EGPs are used to exchange routing information between different autonomous systems, such as on the internet12.
An internet-facing edge router is a router that connects an autonomous system to the internet and acts as a gateway for the traffic entering or leaving the AS3 .
The most common routing protocol for an internet-facing edge router is BGP (Border Gateway Protocol), which is an EGP that enables routers to exchange routing information and reachability information for IP prefixes across the internet12 .
BGP is designed to handle the large and complex topology of the internet, as well as the policy and security requirements of different autonomous systems12 .
Therefore, option A is the correct answer, as BGP is the routing protocol that a technician will most likely use for an internet-facing edge router.
The other options are incorrect, as they are IGPs that are not suitable for an internet-facing edge router.
Option B is incorrect because RIPv2 (Routing Information Protocol version 2) is an IGP that uses hop count as the metric to select the best path12. RIPv2 is an outdated and inefficient routing protocol that has a maximum hop count of 15 and does not support VLSM (Variable Length Subnet Masking)12.
Option C is incorrect because OSPF (Open Shortest Path First) is an IGP that uses link state information and the Dijkstra algorithm to calculate the shortest path to each destination12. OSPF is a widely used and scalable routing protocol that supports VLSM, hierarchical design, and fast convergence12. However, OSPF is not an EGP and cannot exchange routing information between different autonomous systems12.
Option D is incorrect because EIGRP (Enhanced Interior Gateway Routing Protocol) is an IGP that uses a hybrid of distance vector and link state information to select the best path based on bandwidth, delay, reliability, and load12. EIGRP is a Cisco proprietary routing protocol that supports VLSM, fast convergence, and unequal cost load balancing12. However, EIGRP is not an EGP and cannot exchange routing information between different autonomous systems12.
Reference:
1: CompTIA Network+ N10-008 Study Guide, Chapter 4, Section 4.1, "Routing Concepts", page 198-207.
2: Professor Messer's CompTIA N10-008 Network+ Course Notes, Section 4.1, "Routing Concepts", page 24-25.
3: CompTIA Network+ N10-008 Study Guide, Chapter 4, Section 4.2, "Routing Protocols", page 208-209.
4: Professor Messer's CompTIA N10-008 Network+ Course Notes, Section 4.2, "Routing Protocols", page 26.
5: CompTIA Network+ N10-008 Study Guide, Chapter 4, Section 4.2, "Routing Protocols", page 210-211.