What type of OSPF router generates a type 2 LSA?

In OSPF, a Type 2 Link State Advertisement (LSA), also known as a Network LSA, is generated exclusively by the Designated Router (DR) on a multi-access network segment (such as Ethernet). The purpose of the Network LSA is to describe all the routers that are connected to that specific network segment. This mechanism reduces the number of adjacencies required on the segment, thereby optimizing the flooding of LSAs and the size of the link-state database. The LSA is flooded only within the area to which the network segment belongs.

A. An Area Border Router (ABR) generates Type 3 (Summary) and Type 4 (ASBR Summary) LSAs to advertise routes between different OSPF areas.
B. An Autonomous System Boundary Router (ASBR) generates Type 5 (AS-External) or Type 7 (NSSA-External) LSAs to advertise routes from outside the OSPF domain.
D. All routers within an OSPF area generate Type 1 (Router) LSAs to describe their own directly connected links within that area.

1. Nokia Interior Routing Protocols Student Guide (SR OS 21.10): In the module covering OSPF fundamentals, it is specified that "Type 2: Network LSA - Originated by the Designated Router (DR) on a broadcast or NBMA network. Describes all routers attached to the multi-access network. Flooded within the area only." (Reference: Module 3: OSPF, Section: OSPF LSAs).

2. RFC 2328 - OSPF Version 2: This is the foundational standard for OSPFv2. Section 12.4.2, "Network-LSAs," explicitly states: "Network-LSAs are originated by the Designated Router for the network. The LSA describes all routers attached to the network (including the Designated Router itself)."

3. Nokia Service Router OS I - Interior Routing Protocols Courseware: The course material for the 4A0-113 exam details the function of each LSA type. It confirms that the Designated Router is the sole originator of Type 2 LSAs for its designated network segment. (Reference: Chapter on OSPF Link-State Advertisements).