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During a CEF packet rewrite, which of the following changes are NOT made to the packet?
A. The source MAC address is changed to the MAC address of the outbound Layer 3 switch interface.
B. The destination MAC address is changed to the MAC address of the next-hop router’s MAC address.
C. Layer 3 TTL is decremented by one.
D. Layer 2 TTL is decremented by one.
Correct Answer: D
Explanation/Reference:
Answer:
There is no Layer 2 TTL in the packet, so the Layer 2 time to live (TTL) cannot be decremented by one. All other options are correct. The following changes will be made when the Cisco Express Forwarding (CEF) packet rewrite process occurs:
The source MAC address is changed to the MAC address of the outbound Layer 3 switch interface.
The destination MAC address is changed to the MAC address of the next hop routers MAC address
The Layer 3 IP TTL is decremented by one
The Layer 3 IP checksum is recalculated
The Layer 2 frame checksum is recalculated
Objective:
Layer 2 Technologies Sub-Objective:
Configure and verify switch administration
References:
Cisco > Catalyst 6500 Series Cisco IOS Software Configuration Guide, 12.1E > Configuring IP Unicast Layer 3 Switching on Supervisor Engine 2 > Understanding How IP Multicast Layer 3 Switching Works
