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352-001 · Question #166
352-001 Question #166: Real Exam Question with Answer & Explanation
The correct answer is C: Switch C. With IEEE 802.1w (RSTP), placing the spanning-tree root at the distribution-layer switches closest to the affected VLANs minimizes topology changes and enables rapid failover for clients in VLANs 3 and 4.
Question
Refer to the exhibit. If IEEE 802.1w is in use for this network design, what are two locations where spanning-tree root can be placed to ensure the least-disruptive Layer 2 failover for clients within VLANs 3 and 4? (Choose two.)
Exhibit
Options
- ASwitch A
- BSwitch B
- CSwitch C
- DSwitch D
Explanation
With IEEE 802.1w (RSTP), placing the spanning-tree root at the distribution-layer switches closest to the affected VLANs minimizes topology changes and enables rapid failover for clients in VLANs 3 and 4.
Common mistakes.
- A. Placing the root at Switch A, a core or remote switch, means that any failure requires reconvergence across more of the topology, increasing disruption time for VLAN 3 and 4 clients.
- B. Switch B is not directly adjacent to the segments hosting VLANs 3 and 4, so root placement there increases the spanning-tree diameter and the number of switches affected during a failover event.
Concept tested. RSTP root placement for optimal Layer 2 failover
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