What criteria is used first during the root port selection process?
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A. B. C. D.B
In the Spanning Tree Protocol (STP) process, the root port is the port on a non-root bridge that has the lowest cost path to the root bridge. The root port selection process begins with the comparison of the cost of each interface to reach the root bridge.
Therefore, the correct answer is B. The lowest path cost to the root bridge is the first criteria used during the root port selection process.
If multiple interfaces on a switch have the same path cost to the root bridge, the following criteria will be used in the order listed below:
The lowest neighbor's bridge ID - If two or more ports have the same cost to the root bridge, the bridge ID of the neighbor is compared, and the lowest bridge ID wins.
The lowest neighbor's port ID - If two or more ports have the same cost and bridge ID, the neighbor port ID is compared, and the lowest wins.
The local port ID - If two or more ports have the same cost, bridge ID, and neighbor port ID, then the local port ID is compared, and the lowest wins.
In summary, the root port selection process begins with the lowest cost path to the root bridge and proceeds with bridge ID, neighbor port ID, and local port ID as tiebreakers, if necessary.