By default, which of the following factors determines the spanning-tree path cost?

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问题 By default, which of the following factors determines the spanning-tree path cost?

选项 A、It is the individual link cost based on latency
B、It is the sum of the costs based on bandwidth
C、It is the total hop count
D、It is dynamically determined based on load
E、None of the above

答案B

解析 Explanation:
"The STP cost is an accumulated total path cost based on the available bandwidth of each of the links."

Note: A path cost value is given to each port. The cost is typically based on a guideline established as part of 802.1d. According to the original specification, cost is 1,000 Mbps (1 gigabit per second) divided by the bandwidth of the segment connected to the port.

Therefore, a 10 Mbps connection would have a cost of (1,000/10) 100.
To compensate for the speed of networks increasing beyond the gigabit range, the standard cost has been slightly modified. The new cost values are:


You should also note that the path cost can be an arbitrary value assigned by the network administrator, instead of one of the standard cost values.

Incorrect Answers:
A, D: The STP process does not take into account the latency or load of a link. STP does not recalculate the link costs dynamically.

C. Hop counts are used by RIP routers to calculate the cost of a route to a destination. The STP process resides at layer 2 of the OSI model, where hop counts are not considered.
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