Cisco Certified Internetwork Expert (CCIE) Practice Test 2026 – Your Complete All-in-One Guide to Exam Success!

The most likely reason for the failure of the EtherChannel configuration is that the EtherChannel requires three ports, and only two are configured. EtherChannel technology relies on grouping multiple physical links into a single logical link to enhance bandwidth and provide redundancy. However, there are specific requirements regarding how many ports must be configured to establish an EtherChannel successfully.

In a standard EtherChannel configuration, it is common to require at least two ports, but during some implementations, a minimum of three or a specific number can be necessary based on the chosen mode or protocol. If the configuration only includes two ports and three are needed, the EtherChannel will not establish correctly.

Mismatched channel-group modes (the first option), or identical lacp system-priority and port-priority values (the second option), can cause issues, but these relate to incorrect settings rather than the fundamental requirement of having a sufficient number of ports. The fourth option regarding the EtherChannel being disabled would be a straightforward cause of failure, but it does not address the core concern of the port requirements.

In summary, when the specified number of ports needed for the EtherChannel is not met, the configuration is inherently incomplete, leading to a failure in establishing the channel, highlighting the importance of adhering to