Cisco Certified Network Professional Practice Test 2025 – Your All-in-One Guide to Exam Success!

A switch port that is not configured does not inherently cause a CEF punt. CEF operates by maintaining a Forwarding Information Base (FIB) and using optimal paths for fast packet forwarding through the network. When a switch port is unconfigured, packets arriving on that port will not be processed or forwarded but may simply be dropped. However, this action does not result in a punt to the CPU for further processing, as it is not a legitimate forwarding path or a decision that necessitates CPU involvement.

In contrast, when the FIB table is full, the system cannot add new routes, which can lead to packets being punted to the CPU for additional processing. Similarly, when the Time-to-Live (TTL) of a packet expires, it must be handled by the CPU to send an ICMP "Time Exceeded" message. Fragmentation requires additional processing as well, especially if the packet size exceeds the Maximum Transmission Unit (MTU), often leading to a punt for reassembly or other handling. These conditions necessitate CPU intervention, whereas an unconfigured switch port simply results in packet loss without needing such processing.