Which of the following OSPF areas have specific limitations or rules? (Choose two)

OSPF allows for the creation of special area types to control the advertisement of routing information, which helps to reduce the size of the link-state database and routing tables on routers. A Stub Area is a restricted area that does not allow Type 5 LSAs (external routes) to be flooded into it; instead, the Area Border Router (ABR) injects a default route. A Not-So-Stubby Area (NSSA) is a variation that also blocks Type 5 LSAs from other areas but allows an Autonomous System Boundary Router (ASBR) within the NSSA to inject external routes using Type 7 LSAs. Both are defined by these specific LSA filtering rules and limitations.

A. Backbone Area (Area 0): The backbone area has a special rule that all other areas must connect to it, but it does not have LSA filtering limitations; it accepts all LSA types.

D. External Area: This is not a valid or standard term for an OSPF area type. OSPF deals with external routes, but not "external areas."

- RFC 2328

"OSPF Version 2

" Section 3.6

"Stub areas." This section defines the concept and limitations of stub areas

specifically the exclusion of AS-external-LSAs (Type 5).

- RFC 3101

"The OSPF Not-So-Stubby Area (NSSA) Option." This document defines the NSSA

its purpose

and the rules governing Type 7 LSAs.

- Juniper Networks TechLibrary

"Junos OS Routing Protocols Library for Routing Devices

" OSPF Overview

"OSPF Area Types." This guide describes the characteristics of backbone

standard

stub

and not-so-stubby areas.