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391 Which Distance Vector
characteristic can help to speed up convergence?
A.) Triggered Updates.
B.) Split Horizon.
C.) Poison Reverse.
D.) Hold Down timers.
E.) Inverse ARP.
Ans A
Instead of waiting on a pre-set periodic interval (before
sending the routing table), DV routing protocols can send
triggered updates to immediately notify the neighbor routers.
Hold down timers, Poison Reverse, and Split Horizon are features
that are used to avoid routing loops.
392 Which type of switching is considered to be 'wire speed?'
A.) Cut-Through
B.) Multiplexed
C.) Inverted
D.) Layer 4
E.) Store and Forward
F.) Layer 3
Ans A
Cut-Through is the fastest mode of switching. Store and Forward
reads in the entire frame, confirms the frame is valid, and then
forwards the frame onto the wire. Cut-Through only checks the
destination header in the frame and immediately forwards the
frame onto the wire, without checking the frame to be valid.
Layer-3 switching is actually routing.
393 The Datalink layer works with which of the following:
A.) Packets
B.) Bits
C.) Globules
D.) Frames
E.) Segments
Ans D
Physical - bits
Datalink - frames
Network - packets
394 What is a characteristic of Store and Forward switches?
A.) They forward the frame before it is completely read.
B.) They work at wire speed.
C.) They are the same a Cut-Through switching.
D.) They read the entire frame and check CRC before forwarding.
E.) They decrease latency.
Ans D
Store and Forward switch will not forward fragments.
The longer the frame, the longer the delay (latency) before the
switch can forward.
395 Station A is transmitting data to station B, and expects
an acknowledgment after every 400 bytes. After transmitting data
for a while, the two stations determine the line is reliable and
change to expecting and acknowledgement every 600 bytes.
This is an example of (pick the best answer only):
A.) BECN
B.) Sliding Windows
C.) Poison Reverse
D.) Countdown timers
E.) Split Horizon
F.) Count to infinity
Ans B
A TCP/IP 'window' is the amount of data (number of bytes) that
the sending station will transmit before expecting an
acknowledgement back.
If the stations can change that window size on the fly, that is
called a sliding window. This is done to optimize performance.
396 Which device listed below provides clocking for the line?
A.) DCE
B.) CPE
C.) CO
D.) DTE
E.) Demarc
Ans A
The Data Circuit-terminating Equipment (DCE) is responsible for
providing the clocking on the wire.
HINT: When You see the 'C' in 'DCE', think 'Clocking' t.
397 Which OSI Reference Layer controls application to
application communication?
A.) Datalink
B.) Network
C.) Transport
D.) Session
E.) Physical
Ans D
The Session layer controls a conversation between applications.
The Transport layer controls communications between hosts.
398 The Datalink Layer is broken down into 2 layers, LLC and
MAC. The LLC establishes media independence and what else?
A.) Provides Windowing.
B.) Provides flow control.
C.) Provides SAP's (Service Access Points).
D.) The Datalink layer does not have sublayers.
E.) Provides SAP's (Service Advertising Protocol).
F.) RIP Updates.
Ans B C
OSI layer-2 SAP allows the upper layers to encapsulate multiple
layer 3 protocols.
IPX SAP is a protocol used to advertise NetWare services every
60 seconds.
399 When a Distance Vector routing protocol detects that a
connected network has gone down, it sends out a special routing
update packet, telling all directly connected routers that the
distance to the dead network is infinity. This is an example of
which routing technology?
A.) ICMP.
B.) Only Link State routing protocols have this intelligence.
C.) Triggered updates.
D.) Garrison-4.
E.) Split Horizon.
F.) Poison Reverse.
Ans F
Instead of just removing the route from the routing update,
Poison Reverse sets the distance to 'infinity' (for IP RIP this
is a hop count of 16). This immediately makes the route invalid
for all neighboring routers.
400 Which of the following would be displayed by the command
'SHOW CDP NEIGHBOR DETAIL'?
A.) The incoming/outgoing port.
B.) The hardware platform.
C.) One address per protocol.
D.) Amount of Flash Memory Available
E.) The routers hostname.
F.) The subnet mask, if IP is configured.
Ans A B C E
CDP shows a lot of the same info that 'show version' does
locally, but FLASH memory is not part of it. The 'detail'
keyword is optional, but even when used, IP subnet mask
information is not displayed by CDP for IP interfaces.
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