单项选择题CiscoExpressForwarding(CEF)ismainlyusedtoincreasepacketswitchingspeed,reducingtheoverheadanddelaysintroducedbyotherroutingtechniques,increasingoverallperformance.WhichofthefollowingconcerningCEFisrecommendedbyCisco?()
A. Use default Layer 4 hash in core.
B. Use default Layer 3 hash in distribution.
C. Use default Layer 4 hash in distribution.
D. Use default Layer 3 hash in core and Layer 3 + Layer 4 hash in distribution layer.