The exhibit shows the configuration of RSTP on EX-4, which has the command  force-version stp .  This command forces the switch to use the legacy STP protocol instead of RSTP, even though the switch supports RSTP 1 .  This means that EX-4 will not be able to take advantage of the faster convergence and enhanced features of RSTP, such as edge ports, link type, and proposal/agreement sequence 2 .

The other switches in the network are likely to be running RSTP, as it is the default protocol for EX Series switches 3 . Therefore, there will be a compatibility issue between EX-4 and the other switches, which will result in longer convergence times and suboptimal performance.  The switch will also generate a warning message that says “Warning: STP version mismatch with neighbor” when it receives a BPDU from a RSTP neighbor 1 .

To solve this problem, the force-version command must be removed from EX-4, so that it can run RSTP natively and interoperate with the other switches in the network. This will enable faster convergence and better stability for the network topology.  To remove the command, you can use the  delete protocols rstp force-version  command in configuration mode 1 .

 In OSPF, a DR (Designated Router) and a BDR (Backup Designated Router) are elected on each multi-access network, such as Ethernet or Frame Relay. The DR and BDR are responsible for exchanging routing information with other routers on the same network segment. The election is based on two criteria: the OSPF priority and the router ID. The router with the highest priority becomes the DR, and the router with the second-highest priority becomes the BDR. If the priorities are equal, the router with the highest router ID becomes the DR, and the router with the second-highest router ID becomes the BDR. The default priority is 1, and the router ID is either manually configured or derived from the highest IP address on any interface12.

In this scenario, R1 has a priority of 32 and a router ID of 192.168.1.2, and R2 has a priority of 64 and a router ID of 192.168.1.1. Since R2 has a higher priority than R1, it will become the BDR. The router ID does not matter in this case, because the priority is different. Therefore, the correct answer is C.

The other options are not correct because:

A. At least two routers are required for a DR/BDR election, not three2.

B. Router IDs do not have to match for an adjacency to form, they just have to be unique3.

D. R1 will not be the BDR, because it has a lower priority than R212.