Which two options are IEEE variants of STP? (Choose two.)
- MSTP
- VRRP
- RSTP
- Rapid PVST+
- PVST+
Explanation: The Spanning Tree Protocol (STP) has evolved through several standards to provide loop-free redundancy, with RSTP and MSTP being the two primary variants defined by the IEEE. RSTP, or IEEE 802.1w, was developed to address the slow convergence of the original 802.1D standard, allowing network ports to transition to a forwarding state much faster. MSTP, or IEEE 802.1s, further enhances network efficiency by grouping multiple VLANs into a single spanning tree instance, which significantly reduces the processing load on the switch's CPU. In contrast, options such as PVST+ and Rapid PVST+ are Cisco-proprietary enhancements rather than standard IEEE variants, although they incorporate IEEE functionalities to provide per-VLAN spanning tree instances. VRRP is not a part of the spanning tree suite at all, as it is an open-standard protocol used for default gateway redundancy. Therefore, MSTP and RSTP are the only official IEEE standards among the choices provided.
Related exam: Modules 1 – 7: Checkpoint Exam: Network Switching Answers (CCNP ENCOR v9)
