WhatisoneofthereasonsthatcustomQoSACLsarerecommendedoverautomaticQoSwhen configu
A.79xxIPphonesdonotautomaticallymarkvoicepacketswithnon-zeroDSCPvalues.
B.79xxIPphonesdonotmarkprotocolpacketssuchasDHCP，DNS，orTFTPwithnon-zero DSCPvalues.
C.79xxIPphonesdonotmarkvoicepacketswithoptimalDSCPvalues.
D.79xxIPphonesuseacustomprotocoltocommunicateCDPinformationtotheswitch.
正确答案：参考C
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