Which protocol is utilized when there are multiple routes to the same destination/mask pair from various sources?

The correct choice highlights the role of eBGP (External Border Gateway Protocol) in scenarios with multiple routes to the same destination/mask pair from different sources. eBGP is primarily used for exchanging routing information between different autonomous systems (AS) on the internet.

In networks where multiple connections to external networks exist, eBGP allows routers to learn about various paths to the same destination. This is critical in making informed routing decisions based on various attributes such as path length, next-hop accessibility, and policy-based preferences. It enables the selection of the most optimal route among multiple available paths, thus ensuring efficient traffic management and redundancy.

The other options are more specific to either internal communication within an AS or less effective in handling multiple external routes. iBGP (Internal BGP) is used within an AS to learn about routes given by eBGP but does not directly manage multiple paths from different sources. RIP (Routing Information Protocol) has limitations in the number of hops it can consider and is generally less efficient for larger networks, while EIGRP (Enhanced Interior Gateway Routing Protocol) is designed for optimizing routing within a single AS, not specifically for handling multiple external routes.