Which two of these are characteristics of the 802.1Q protocol? (Choose two.)

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QUESTION 51

Which two of these are characteristics of the 802.1Q protocol? (Choose two.)

A. It modifies the 802.3 frame header, and thus requires that the FCS be recomputed.

B. It is used exclusively for tagging VLAN frames and does not address network reconvergence following switched network topology changes.

C. It is a Layer 2 messaging protocol which maintains VLAN configurations across networks.

D. It is a trunking protocol capable of carrying untagged frames.

E. It includes an 8-bit field which specifies the priority of a frame.

Correct Answer: AD

Section: Switching

Explanation

Explanation/Reference:

802.1q inserts a new section into the frame header which holds the 12-bit VLAN id for the frame and a 3-bit priority value (thus, not E). Thus, the frame’s contents

are changed, and the FCS checksum must be recalculated (A). It also includes MSTP to perform Spanning Tree across multiple VLANs (rules out B). Frames

belonging to the native VLAN do not carry VLAN tags when sent over the trunk. Conversely, if an untagged frame is received on a trunk port, the frame is

associated with the native VLAN configured on that port (D is true).