N10-009 Network Implementation 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.

• ✓

  The router with the highest router ID

  Why this is correct

  In OSPF, the Designated Router (DR) election process first considers the OSPF priority configured on the interface. If multiple routers have the highest priority (default is 1), the tie-breaker is the router with the highest OSPF Router ID. This ensures a deterministic election on multi-access segments, facilitating efficient LSA flooding and reducing the number of adjacencies needed among all routers.

• ✗

  The router with the lowest IP address on the segment

  Why it's wrong here

  While IP addresses are fundamental to network communication, the OSPF DR election process does not use the lowest IP address configured on the segment. Instead, it primarily relies on the OSPF interface priority and, as a tie-breaker, the OSPF Router ID. The Router ID is typically the highest loopback IP address or highest active interface IP, not necessarily the lowest IP on the segment, ensuring a unique identifier for the router.

  When this WOULD be correct

  In a scenario where the question asks about the Backup Designated Router (BDR) election and all routers have the same priority, the BDR is the router with the highest router ID among non-DR routers. However, if the question specified that the DR is already elected and the BDR fails, the next BDR is chosen based on highest router ID, not lowest IP.

• ✗

  The router with the highest bandwidth on the connecting interface

  Why it's wrong here

  Interface bandwidth, while crucial for OSPF cost calculation and path selection, plays no role in the Designated Router (DR) election on a multi-access segment. The DR election mechanism is strictly based on OSPF interface priority and the OSPF Router ID. Bandwidth influences the metric for routing decisions, not the administrative role of a router in managing LSA exchanges on a shared segment.

  When this WOULD be correct

  In a scenario where the question asks about the selection of the active router in a Virtual Router Redundancy Protocol (VRRP) group with default priority, the router with the highest interface bandwidth might be chosen if the election is based on a non-standard configuration or if the question specifically mentions a proprietary feature like Cisco's 'priority' command that can be tied to bandwidth.

• ✗

  The router with the oldest uptime

  Why it's wrong here

  The uptime of a router, or how long it has been operational, is not a factor in the OSPF Designated Router (DR) election process. OSPF relies on specific parameters like interface priority and Router ID to determine the DR and Backup Designated Router (BDR). Network stability metrics like uptime do not contribute to the election algorithm, which focuses on administrative and unique identifiers.

  When this WOULD be correct

  In a scenario where the question asks about the root bridge election in a Spanning Tree Protocol (STP) network with default priorities, the switch with the oldest uptime (lowest bridge ID) becomes the root bridge if all other factors are equal.

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?”