Routing and Route Aggregation

Correct Answer: Summary route

The best option in this scenario is to use a 'Summary route'. Route summarization, also known as route aggregation, is a method of making routing more efficient by reducing the number of individual routes that need to be known by a router. In a situation where a router has interfaces connected to a WAN, LAN, and multiple branch networks, utilizing summary routes can significantly decrease routing overhead. The 'Default route' is a setting on a router that specifies where to send packets for destinations not listed in the routing table. It's typically used when a network has a single connection to the internet, and thus doesn't apply in this multi-branch scenarioA 'Floating static route' is a static route that the router uses as a backup to a dynamic route. It's typically used for redundancy and wouldn't be effective in reducing the number of propagated routes'Supernetting' or Classless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and IP routing, but it isn't a type of route aggregation and thus would not be the best choice in this situation.

Correct Answer: Redistribution between BGP and OSPF

Redistribution between BGP and OSPF is the correct answer. Border Gateway Protocol (BGP) is used to exchange routing information for the internet and is the protocol used between internet service providers (ISP) while Open Shortest Path First (OSPF) is an interior gateway protocol designed to distribute routing information within a single Autonomous System (AS). The process of passing route information from one routing protocol to another is called redistribution. Here, the network administrator seeks to share routes between BGP (a protocol used between different AS) and OSPF (a protocol used within an AS). Redistribution is the process that achieves this. On the other hand, Dynamic routing over GRE does not solve the requirement, as this is a tunneling protocol that can encapsulate a wide variety of network layer protocols inside virtual point-to-point links. An OSPF stub area also does not directly address the goal since it is a specific type of area in OSPF that restricts the types of routes that can propagate into the area. Lastly, a BGP route reflector is a mechanism in BGP that allows certain network routers to re-advertise BGP routes, and it does not necessarily deal with the distribution of routes to internal routers using OSPF.

Correct Answer: OSPF

The Open Shortest Path First (OSPF) protocol is the best choice in this scenario. OSPF is a link-state routing protocol that can quickly adapt to changes in a network's topology, which makes it an ideal choice for an environment with frequent topology changes. It also effectively utilizes the available bandwidth by choosing the shortest path based on various metrics such as hop count, speed of the path, and reliability, among others. RIP (Routing Information Protocol) is not as efficient because it uses hop count as its only metric and doesn't consider network speed. BGP (Border Gateway Protocol) is used for routing between autonomous systems (Internet Service Providers) and is not the best choice for internal routing in a company. IS-IS (Intermediate System to Intermediate System) is a bit complex to configure and mainly used in large networks like ISPs.