Refer to the exhibit. Which routing solution is the most scalable to connect the branches to the HQ and to connect the branches together over the internet using DMVPN?

EIGRP without stub configuration causes all branch routers to participate in the full query domain, leading to SIA issues and poor scalability across hundreds of sites.

In large DMVPN deployments, configuring branch routers as EIGRP stubs prevents them from being included in EIGRP query propagation, which dramatically reduces convergence time and avoids stuck-in-active (SIA) conditions. Stub routers only advertise their local and summary routes, keeping the routing table on hub routers manageable as the number of branches grows to large scale.

Configuring every branch as an OSPF ABR is operationally complex and requires each branch to maintain and exchange LSAs for multiple areas, which does not scale well for large branch deployments.

IS-IS Level 2 is typically used for large service provider backbones and does not offer the spoke-stub optimization needed for hub-and-spoke DMVPN branch scalability.

Placing all locations in OSPF Area 0 creates a single flat LSA database that grows with every site added, making convergence time and memory consumption unmanageable at large scale.