Transcript cut-through

CCNA 1 v3.1
Module 8 Review
Which switching mode describes a
switch that transfers a frame as
soon as the destination MAC
address is read?
• cut-through
2
What does a switch broadcast to let
other switches know of its existence
on the LAN?
• BPDUs
3
What network type uses
networking devices to extend the
distances that cable can be run?
• extended shared media
4
What is the term associated
with replacing hubs with
switches to increase the
number of collision domains?
•segmentation
5
While working on her computer, Mary noticed
longer than normal network data transfers.
Mary investigates the problem and notices that
her co-worker John has been hosting an online
video conference. What is the network
probably experiencing?
• A broadcast storm
6
What does a router use to
make a forwarding decision?
• destination IP address
7
A network administrator has a multifloor LAN to monitor and maintain.
Through careful monitoring, the
administrator has noticed a large
amount of broadcast traffic slowing
the network. Which device would
you use to best solve this problem?
• A router, or as they say in Great
Britain, a rooter.
8
What is a disadvantage of cutthrough switching?
• no error checking
9
What are two things that would
alleviate the problem of excessive
collisions in a LAN?
• reduce the size of collision
domains
• add extra managed switches
10
What protocol is used to
eliminate switching loops?
• Spanning Tree Protocol
11
Name the OSI layers at which
each device operates:
•
•
•
•
•
Router
Switch
Repeater
Bridge
Hub
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•
•
•
•
Layer 3
Layer 2
Layer 1
Layer 2
Layer 1
12
Which of the following are not to be
exceeded when implementing the
5-4-3-2-1 Rule? (Choose three.)
•
•
•
•
•
five broadcast domains
four hubs
three routers
three host segments
one collision domain
13
What describes the concept
of full-duplex mode?
• traffic passing equally in both
directions with no collisions
14
Which switching mode has the
lowest latency?
• cut-through
Why?
• Because it reads the beginning of the frame up to
the destination MAC address as the traffic flow
through the switch and “cuts through” to its
destination without continuing to read the rest of
the frame.
15
What are two ways in which a
bridge has an impact on a
network?
• increases number of collision
domains
• has no impact on broadcast
domains
16
What are two items that are
contributors to latency in a
switched network?
• circuit delays
• software delays
17
What are 2 devices that perform the
tasks of viewing and forwarding
frames based on MAC addresses?
• switch
• bridge
18
What does a switch build as it
reads MAC addresses that pass
through it?
• Content Addressable Memory
table
19
What will a bridge do if it receives a
frame with a MAC address that is not
within the table?
• send frame to all ports except
source port
20
A switch reads the first 64 bytes of a
data field and forwards data, before
the entire data field has been read.
Which switching method allows
this?
• fragment-free
21
What are the three switching modes?
• store-and-forward
• fragment-free
• cut-through
Which switching mode has the highest latency?
• store-and-forward
Why?
• Because it reads the entire frame, checks for
errors, decides where it needs to go, and then
sends it on its way.
22
What does a workstation
broadcast to learn an unknown
MAC address?
• ARP request
23