What are three traffic descriptors typically used to categorize traffic into different classes？（） A: IP precedence B: media type C: DSCP D: outgoing interface E: incoming interface F: DLCI

Which two options can be used as traffic descriptors when classifying and marking traffic？ （） A: incoming interface B: Layer 2 differentiated services code point （DSCP） C: Layer 3 IP precedence D: outgoing interface

Which one of the following statements is right? A: If a local variable has static storage duration, its lifetime will be extended. B: If a global variable has static storage duration, its scope will be expanded. C: A variable will have an unpredictable value before initialization; no matter it has static storage duration or automatic storage duration. D: The storage type descriptors which formal parameter can use are exactly the same as that used by the local variables.