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PortFast Questions

November 20th, 2018 in SWITCH 300-115 Go to comments

Question 1

Explanation

If a BPDU is received on a port where BPDU guard is configured, that port is put into errdisable state (nearly the same as shutdown state) immediately. BPDU Guard is often configured on a PortFast-enabled port to prevent a switch from connecting to. When that switch begins to send BPDU to a BPDU guard port, it will be blocked immediately.

Question 2

Question 3

Question 4

Explanation

The Portfast feature can be configured on both access or trunk port. This feature instructs the port to skip listening and learning state and move to forwarding state immediately.

“Skip 802.1D timers” here means “skip the listening and learning timers” so in fact these two answers have same meanings.

Question 5

Comments
  1. trueteller
    December 17th, 2018

    Q3

    For sure C is correct however I am not sure about D answer:

    https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_55_se/configuration/guide/3560_scg/swstpopt.html#41777

    “Port Fast immediately brings an interface configured as an access or trunk port to the forwarding state from a blocking state, bypassing the listening and learning states. You can use Port Fast on interfaces connected to a single workstation or server, as shown in Figure 18-1, to allow those devices to immediately connect to the network, rather than waiting for the spanning tree to converge.”
    Learning state is one of the states that it bypass.
    How about B answer instead of D? D is only partially true.

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