單項選擇題What is the effect of turning on all available downstream carrier tones in a DMT DSL transmissionsystems？（）

A.Downstream RS error correction effectiveness is reduced
B.The downstream line rate and throughput remains unchanged， but FEC efficiency is reduced
C.The upstream DSL bandwidth is reduced， since less carriers become available for upstream traffic
D.The downstream DSL bandwidth is increased


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1.單項選擇題Which statement is FALSE concerning the interleave depth value？（）

A.A higher interleave depth provides more protection from burst of noise on the HFC network
B.Higher interleave depth increase downstream latency
C.Lower interleave depth cause some packet loss on typical HFC networks
D.None ofthe above

2.多項選擇題Which two IOS commands are equivalents for putting a Cisco 7500 OC-12 RPR interface card intowrapped mode？ （）

A.shutdown [a b]
B.srp shutdown [a b]
C.srp ips request manual-switched [a b]

5.單項選擇題What is the function of the AJB bits on DS1 using Extended Super Frame （ESF）？（）

A.It is used for signaling on-hook and off-hook status
B.It carries CRC information for error detection
C.It is used for a control and performance information
D.It is used for a frame’s synchronization and alignment

6.單項選擇題During the modem boot process，how does the modem acquire the downstream channel？（）

A.The modem is commanded by the CMTS to set to the specific channel
B.The modem uses the default value in the broadcom chipset
C.The modem tuner sets a level as defined by the DOCSIS specification
D.The modem tuner scans the downstream spectrum until digital QAM modulated signal is encountered

8.單項選擇題What is the effect of changing DMT interleaved delay from 3 milliseconds to 15 milliseconds？（）

A.Latency remains the same， but throughput is decreased.
B.Latency remains the same， but error correction effectives may also be reduced.
C.Latency is increased， but faster error correction occurs.
D.Fewer ATM PVCs can be provisioned on DSL line.

9.單項選擇題When gateways are registering with a gatekeeper， the gatekeeper can be（）.

A.On the same subnet
B.On a remote LAN
C.In a different subnet
D.Any of the above

10.單項選擇題What is the relationship between the Domain Name System （DNS） and LDAP？（）

A.All the root DNS servers maintain information in a distributed LDAP tree.
B.DNS clients access DNS information by making LDAP queries to DNS servers.
C.An LDAP DN attribute is a Domain Name.
D.It is currently recommended to express DN as a sequence of Domain components.

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