In a cable HFC plant， what is a modulator？（）

单项选择题WhatisthepurposeofDualRingInterconnectwithDCforSDHrings？（）

A.Protects signals when a ring switch fails
B.Protects signals when multiple span switches fail
C.Protects pre-emptible traffic from being dropped when a ring switch occurs
D.Protects signals against any combination of link failure in each ring

单项选择题WhatistheeffectofturningonallavailabledownstreamcarriertonesinaDMTDSLtransmissionsystems？（）

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

单项选择题WhichstatementisFALSEconcerningtheinterleavedepthvalue？（）

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

多项选择题WhichtwoIOScommandsareequivalentsforputtingaCisco7500OC-12RPRinterfacecardintowrappedmode？（）

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

单项选择题BGPbestrouteselectionprocessisbasedonpathattributes.（）

A.True
B.False