Which of the following statements regarding Designated Routers (DR) in OSPF are correct?

In OSPF, on multi-access networks, a Designated Router (DR) and Backup Designated Router (BDR) are elected to reduce redundant LSA flooding. The DR and BDR establish full adjacencies with each other and with all other routers (DROthers) on the segment. The election is based first on OSPF interface priority (higher is better). If priorities are equal, the router with the highest Router ID is chosen as the DR. This makes options A and D correct statements describing the process and relationships.

B. The router with the higher OSPF interface priority is elected as the DR, not the one with the lower priority.
C. Routers with an OSPF interface priority of 0 are ineligible and do not participate in the DR/BDR election process. Therefore, not all routers necessarily participate.

1. Huawei HedEx Documentation, HCIA-Datacom V1.0 Training Material, "OSPF Basics", Section: "DR and BDR". This material explicitly states, "If router priorities are the same, the router with the largest router ID is elected as the DR." It also describes the adjacency states, confirming DR and BDR form a full adjacency.

2. Moy, J. (1998). RFC 2328: OSPF Version 2. The Internet Society. Section 9.4, "Electing the Designated Router". This RFC specifies that if priorities are equal, the highest Router ID wins. Section 10.4 describes that DR and BDR become fully adjacent.