A campus site uses two ISPs to provide internet connection - one as the active provider and the other as a backup provider. An engineer is configuring an alert rule in Cisco ThousandEyes to trigger…

Question

Options

• ATrace is incomplete
• BHop #
• CPath Length
• DTarget IP Address

• A
  2% (1)
• B
  11% (5)
• C
  83% (38)
• D
  4% (2)

Explanation

Path Length is correct because when the active ISP fails and traffic reroutes through the backup ISP, the traceroute path changes - going through entirely different upstream routers - which results in a different number of hops to reach the internet. Configuring an alert on Path Length change detects this shift in the number of hops, signaling that failover has occurred.

Why the distractors are wrong:

• A. Trace is incomplete - triggers only when the path trace cannot finish at all (e.g., total connectivity loss or ICMP filtering), not a successful failover to a backup link.
• B. Hop # - monitors a specific hop number in the path, which is too narrow to reliably detect ISP failover across a dynamically changing route.
• D. Target IP Address - the destination IP doesn't change during failover; only the path taken to reach it changes.

Memory tip: Associate "failover = new path = different hop count = Path Length." If the network takes a detour through a backup ISP, the number of routers in the path changes, making Path Length the natural alert trigger for this scenario.

No community discussion yet for this question.