What are two advantages of splitting a larger OSPF area into a number of smaller areas? (Select two )

Splitting a large OSPF domain into multiple smaller areas is a fundamental design principle for scalability. This hierarchical approach contains routing information within an area. When a network topology change occurs, the resulting Link-State Advertisement (LSA) flooding and the intensive Shortest Path First (SPF) algorithm recalculation are confined to the routers within that specific area. This localization prevents instability in one area from affecting others. Consequently, routers maintain smaller Link-State Databases (LSDBs) and routing tables, which significantly reduces the CPU and memory resources required for SPF computations, thereby lowering processing overhead.

A. It extends the LSDB: This is incorrect. Creating areas reduces the size of the LSDB that each router must maintain, as routers only need the full LSDB for their own area.

C. it simplifies the configuration.: This is incorrect. Multi-area OSPF design adds complexity by requiring the configuration of Area Border Routers (ABRs), summarization, and a strict area hierarchy.

E. It reduces the total number of LSAs: This is misleading. While the number of LSAs within a single router's LSDB is reduced, ABRs generate new summary LSAs (Type 3), so the total LSA count in the Autonomous System may not decrease.

1. HPE ArubaOS-CX 10.12 Advanced Routing Guide

Page 181

"OSPF areas" section: "The primary benefits of creating areas are that they reduce the size of the link-state database that routers must maintain and localize the impact of a topology change within an area. Any instability in an area is not advertised to other areas." This directly supports that areas increase stability and reduce the processing required for a smaller LSDB.

2. RFC 2328 - OSPF Version 2

Section 3.1

"Splitting the AS into areas": "With the introduction of areas

it is no longer true that all routers in the AS have an identical link-state database. A router actually has a separate link-state database for each area to which it belongs... The flooding of LSAs is limited to the confines of a single area. This reduces the amount of routing protocol traffic... The size of the link-state database that each router must maintain is also reduced." This confirms that the LSDB size is reduced (lowering processing overhead) and LSA flooding is contained (increasing stability).