A Cisco router receives an IP packet destined for host . The routing table contains multiple candidate routes that match this destination IP address. Place the routing decision criteria in the correct order of precedence used by the router to make its forwarding decision, from first evaluated (highest precedence) at the top to last evaluated (lowest precedence) at the bottom.
- 1Identify candidate routes and select the route with the longest prefix match (most specific subnet mask).
- 2If multiple matching routes have the exact same prefix length, select the route with the lowest Administrative Distance (AD).
- 3If multiple routes have identical prefix lengths and originate from the same routing protocol, select the route with the lowest metric.
- 4If multiple routes for the exact same prefix have identical Administrative Distance and metric values, perform equal-cost load balancing across all valid paths.
Cevap
The correct sequence of router forwarding decision logic criteria from highest to lowest precedence is: 1) Longest Prefix Match, 2) Lowest Administrative Distance, 3) Lowest Metric, and 4) Equal-Cost Load Balancing.
When forwarding an IP packet, a Cisco router evaluates candidate routes in a strict multi-tier hierarchy. First, Longest Prefix Match (LPM) determines the best route by selecting the entry with the most specific subnet mask. Second, if multiple routes match with the exact same subnet mask length, the router compares Administrative Distance (AD) to select the most trustworthy route source. Third, if routes share the exact same prefix length and come from the same routing protocol, the router selects the path with the lowest metric. Finally, if prefix length, AD, and metric are all identical, equal-cost load balancing is applied.
Adım Adım Çözüm
Anahtar Kavram
Router Forwarding Decision Hierarchy (LPM -> AD -> Metric -> ECMP)
Tahmini Süre:2m 0s