What is Step 2 in how a LAN switch forwards a frame?
Answer
add the source MAC address to the MAC address table, with incoming
interface and VLAN ID
determine the VLAN in which the frame should be forwarded
choose the designated port on each LAN segment
place each port in either forwarding or blocking state
Question 2
Question
What are the classes of problems caused by NOT using STP in Redundant
LANs? (Choose all that apply.)
Answer
broadcast storms
prevention of looping
MAC table instability
multiple frame transmission
single frame transmission
Question 3
Question
With STP timers, if the hellos do not show up again within MaxAge time, the
switch reacts by taking steps to change the _________________________.
Answer
forward delay
STP topology
hellos
BIDs
Question 4
Question
During the root election the BID is broken down into its components. If there is
a tie with the lowest bridge ID what is next to be compared?
Answer
the highest bridge ID
the lowest root BID
the lowest switch MAC address
the highest switch MAC address
Question 5
Question
On a nonroot switch, STP places its port that has the least cost to the root,
called that switch’s _____________________________, in forwarding state.
Answer
root cost
root port (RP)
designated port (DP)
LANs port (LP)
Question 6
Question
What are the messages called that are used by switches to exchange information
with each other?
Answer
STPs
BIDs
MAC addresses
BPDU
Question 7
Question
Timer values on the root switch includes the hello time, MaxAge time and
_______________ time.
Answer
forward delay
blocking
reevaluating
switch
Question 8
Question
When a port that formerly blocked needs to transition to forwarding, the switch
first puts the port through two intermediate interface states. (choose the
correct state for each explanation)
A. Like the blocking state, the interface does not forward frames. The switch
removes old stale (unused) MAC table entries for which no frames are
received from each MAC address during this period. These stale MAC tab le
entries could be the cause of the temporary loops.
B. Interfaces in this state still do not forward frames, but the switch begins to
learn the MAC address of frames received on the interface.
Answer
A - Learning
A - Listening
B - Learning
B - Listening
Question 9
Question
The best way to lower STP’s convergence time is to avoid convergence all
together. ___________________________ provides a way to prevent STP
convergence from being needed when only a single port or cable failure
occurs.
Answer
PortFast
EtherChannel
Rerouting
Rapid Spanning Tree Protocol (RSTP)
Question 10
Question
The IEEE cost of 100 is what Ethernet speed?
Answer
10 Mbps
100 Mbps
1 Gbps
10 Gbps
Question 11
Question
What is Step 3 in the steady-state operation when nothing is currently changing
in the STP topology?
Answer
the nonroot switches receive the hello on their root parts
the interface is on the root switch, so it becomes the DP on that link
Steps 1 and 2 repeat until something changes
the root cost of 0, out all its working interfaces (those in forwarding state)