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Difficulty: MediumIPv4 Static Routing

A network administrator is configuring redundant internet connectivity on an edge router. The primary ISP connection is reachable via next-hop IPv4 address 203.0.113.1203.0.113.1, while a secondary backup ISP connection is reachable via next-hop IPv4 address 198.51.100.1198.51.100.1. The administrator must configure a primary default static route and a floating backup default static route so that the backup link is utilized only when the primary link fails. Which TWO commands must be configured on the router to fulfill these requirements?

  1. ip route 0.0.0.0 0.0.0.0 203.0.113.1Answer
  2. ip route 0.0.0.0 0.0.0.0 198.51.100.1 210Answer
  3. C
    ip route 0.0.0.0 0.0.0.0 198.51.100.1
  4. D
    ip route 0.0.0.0 0.0.0.0 203.0.113.1 210

Answer

The router requires two default static routes: one primary route pointing to next-hop 203.0.113.1 using default administrative distance 1 ('ip route 0.0.0.0 0.0.0.0 203.0.113.1'), and one floating static route pointing to next-hop 198.51.100.1 with an administrative distance higher than 1 ('ip route 0.0.0.0 0.0.0.0 198.51.100.1 210').
To establish a primary default static route and a floating backup default static route, the primary path must be configured with a lower administrative distance (default is 1) pointing to 203.0.113.1, and the backup path must be configured with an administrative distance strictly higher than 1 (such as 210) pointing to 198.51.100.1. The router installs the route with the lower administrative distance into the routing table under normal operations. If the primary interface or path fails, the route with administrative distance 210 becomes active.

Step-by-Step Solution

1
Define the primary default static route destination prefix and next-hop address.
Construct the command 'ip route 0.0.0.0 0.0.0.0 203.0.113.1', which defaults to administrative distance 1.
Default static routes use prefix 0.0.0.0 and mask 0.0.0.0 to match any IPv4 destination not explicitly present in the routing table.
2
Configure the secondary floating default static route with a higher administrative distance.
Append an administrative distance value greater than 1 (such as 210) to the secondary next-hop command: 'ip route 0.0.0.0 0.0.0.0 198.51.100.1 210'.
A floating static route remains inactive in the routing table until the lower administrative distance primary route disappears.

Key Concept

Floating Static Route Configuration and Administrative Distance
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Topics

IPv4 Static Routing

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