N10-009 Network Operations Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Faulty transceiver

  Why this is correct

  A malfunctioning Small Form-Factor Pluggable (SFP) or Gigabit Interface Converter (GBIC) transceiver is a common cause of physical interface flapping. These optical or copper modules are responsible for converting electrical signals to optical signals (or vice-versa) and maintaining the physical link. When a transceiver is faulty, it can intermittently fail to establish or maintain a stable physical layer connection, leading to the interface repeatedly going up and down. This sporadic loss of link integrity directly manifests as interface flapping, making it a primary suspect for such symptoms.

• ✗

  High CPU utilization on the router

  Why it's wrong here

  While consistently high CPU utilization on a router can severely degrade network performance, delay packet forwarding, and even cause control plane instability, it typically does not directly cause a physical interface to repeatedly go up and down. High CPU primarily impacts the router's ability to process packets, run routing protocols, or manage its own operating system. The physical link state, which is determined by the transceiver and cabling, remains stable even under heavy CPU load, unless the high CPU is a symptom of a hardware failure affecting the physical layer components.

  When this WOULD be correct

  A question asking about intermittent connectivity or routing instability where the router is unable to process routing updates or keepalives due to high CPU, leading to neighbor flapping or route flapping.

• ✗

  Incorrect SNMP community string

  Why it's wrong here

  An incorrect Simple Network Management Protocol (SNMP) community string would prevent a network monitoring system from successfully polling the router for operational data. While this would certainly impact the ability to monitor the router's status, including interface states, it does not cause the physical interface to actually go up and down. SNMP is a management protocol used for data collection; it has no direct control over the physical layer operation or the link status of network interfaces. The interface would continue to operate normally, but its status would simply not be reportable via SNMP.

  When this WOULD be correct

  This option would be correct in a question like: 'A network monitoring system cannot retrieve data from a router. Which of the following is the MOST likely cause?' where the issue is lack of SNMP access due to mismatched community strings.

• ✗

  Routing protocol misconfiguration

  Why it's wrong here

  Routing protocol misconfigurations, such as incorrect timers, authentication failures, or improper network statements, can certainly lead to "route flapping," where routing entries frequently appear and disappear from the routing table. However, this is a logical issue affecting the routing information base, not the physical state of the interface itself. An interface experiencing route flapping due to protocol issues will still show a stable "up/up" physical and line protocol status, as the underlying hardware connection remains intact.

  When this WOULD be correct

  This would be correct in a question about 'persistent route flapping' where routes are repeatedly added and removed from the routing table due to misconfigured timers or neighbor relationships, causing network instability.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.

Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

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