单项选择题
A.Turning the laser to a specific ITU channel
B.Keeping the signal wavelength "locked" to a specific technology
C.Suppressing FWM and SBS non-linear effects
D.None ofthe above
单项选择题 WhatlayeroftheTMN（telecommunicationsmanagementnetwork）modeldoesCTMfitinto？（）
单项选择题 WhatfeaturessetismostfrequentlyusedtopreventhackersfromfloodingaportwithMAC-addresses？（）
单项选择题 ATT（Attached）bitneedstobesetinthelinkstatePDUsinanIS-ISlevel-1-2routertoindicatethattheyareapotentialexitpointoutofthearea.（）