Q66Network Access
Which spanning-tree enhancement skips the learning and listening states and puts ports directly into the forwarding state?
← → navigate · a answer
Community votes
Discussion · 8
6
B is right
B 4
Selected Answer: B
The right answer is B. PortFast.
PortFast is a feature in the Spanning Tree Protocol (STP) that is used to rapidly move a port from the blocking state to the forwarding state. This feature is usually used for access ports that connect to end devices (such as PCs or servers), which do not generate Spanning Tree Protocol (BPDUs) messages. By using PortFast, the STP learning and listening states are skipped and the port is immediately placed into the forwarding state, reducing the amount of time it takes for the port to move from a blocking to a forwarding state.
3
B is correct
2
Spanning Tree Portfast makes layer 2 switch interfaces enter forwarding state immediately,
skipping the listening and learning states. It should be used on ports connected directly to end hosts
like servers or workstations. Note: If portfast isn’t enabled, DHCP timeouts can occur while STP
converges, causing more problems.
2
B is correct!
1
B is correct
1
PortFast: lets the port go straight to a forwarding state because there is no danger of a loop.
BPDU Guard: If an interface with this enabled receives BPDU from another switch, the interface will be shut down to stop a loop from forming.
Root Guard*: even if it receives a superior BPDU (lower bridge ID) on that interface, the switch will not accept the new switch as the root bridge. The interface will be disabled.
Loop Guard*: even if the interface stops receiving BPDUs, it will not start forwarding. The interface will be disabled.
* = not mentioned in objectives.
1
A. BPDUfilter: This feature turns off the processing of received BPDUs on a port, but it does not alter the operation of the Spanning Tree Protocol.
C. Backbonefast: This feature is used to quickly detect and recover from indirect failures in the network, but it does not alter the operation of the Spanning Tree Protocol on individual ports.
D. BPDUguard: This feature helps stop unauthorized switches from being connected to the network by disabling a port if it receives a BPDU message. This can help prevent unauthorized switches from affecting the operation of the Spanning Tree Protocol.