The PIM Bootstrap Router (BSR) mechanism is designed to elect a single, unique BSR for an entire PIM domain. Candidate-BSRs (c-BSRs) exchange Bootstrap Messages (BSMs) containing their priority and IP address. Through an election process, the c-BSR with the highest priority (or highest IP address as a tie-breaker) is chosen as the active BSR. In a stable, converged network, all routers will agree on this single BSR. The existence of multiple elected BSRs would indicate a network partition or a state of non-convergence, contradicting the premise of a "converged multicast network."

A. A router can be configured as both a candidate-BSR and a candidate-RP. This is a common configuration where a router participates in the BSR election and also advertises itself as an available RP.

B. A router can be configured as a candidate-BSR while also being configured as a static RP. The two mechanisms (dynamic BSR discovery and static RP configuration) can coexist on the same device.

C. A router can be configured as a candidate-RP for dynamic discovery while also being configured as a static RP. These are distinct configuration roles that are not mutually exclusive on a single router.

E. The BSR's primary function is to collect advertisements from multiple candidate-RPs and distribute a consolidated RP-set to all routers. This allows for multiple active RPs for different group ranges or for redundancy.

1. Nokia 7750 SR OS Release 19.10.R1 Multicast Routing Protocols Guide, Page 118, Section "PIM Bootstrap Router": "In a PIM domain, a single router is elected as the BSR from a set of candidate BSRs. The BSR is responsible for collecting C-RP advertisements and disseminating the group-to-RP mapping information in Bootstrap messages (BSMs)." This confirms a single BSR is elected and that it collects information from potentially multiple C-RPs.

2. RFC 5059: Bootstrap Router (BSR) Mechanism for PIM, Section 1, Introduction: "With BSR, a single router in a PIM domain is elected as the Bootstrap Router (BSR) from a set of candidate BSRs." This statement from the governing standard explicitly states that the outcome of the election is a single BSR.

3. RFC 5059: Bootstrap Router (BSR) Mechanism for PIM, Section 3.1, BSR Election: "The BSR election procedure selects a single BSR for a PIM domain. Each C-BSR, upon receiving a BSM, compares its own BSR priority and address with that of the BSR that originated the received BSM..." This details the mechanism that ensures only one BSR is elected.