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Difficulty: Very hardIPv4 Static Routing

A network administrator needs to configure reliable static default routing on a Cisco IOS router by tying a primary static route to an IP SLA probes object, ensuring that the route is automatically withdrawn if the target becomes unreachable. Arrange the operational and CLI configuration steps in the correct chronological order from establishing the probe metric to static route activation.

  1. 1Define the IP SLA probe instance (e.g., `ip sla 1`) and configure the ICMP echo target IP address 203.0.113.1203.0.113.1 along with its execution schedule (`ip sla schedule 1 life forever start-time now`).
  2. 2Create an object tracking process (`track 10 ip sla 1 reachability`) to monitor the state and reachability metric returned by the IP SLA probe.
  3. 3Configure the primary default static route referencing the tracking object using the CLI syntax: `ip route 0.0.0.0 0.0.0.0 198.51.100.1 track 10`.
  4. 4The router verifies that tracking object 1010 is in the UP state following successful ICMP responses and installs the static route into the Routing Information Base (RIB).

Answer

The correct chronological sequence is: (1) Define and schedule the IP SLA probe instance, (2) Create the object tracking process monitoring IP SLA reachability, (3) Configure the static route bound to the track object ID, and (4) Verify probe success leading to tracking state UP and RIB installation.
The correct sequence follows the mandatory dependency hierarchy in Cisco IOS: first, the IP SLA engine must be defined and scheduled to generate active probes; second, a tracking object must be constructed to translate probe results into a boolean UP/DOWN status; third, the IPv4 static route must be configured with the `track` keyword; and finally, once the tracking object confirms reachability (UP state), the router installs the static route into the routing table (RIB).

Step-by-Step Solution

1
Configure and schedule the IP SLA ICMP Echo probe operation.
The router begins sending ICMP echo packets to target IP 203.0.113.1203.0.113.1.
Tracking objects require an active underlying probe instance to supply reachability status.
2
Bind the IP SLA operation to a tracking object ID using `track <id> ip sla <ops-number> reachability`.
Tracking object status changes to UP when SLA probe responses are received successfully.
Static routes cannot monitor IP SLA probes directly; they must reference a tracking object.
3
Apply the `ip route` global configuration command specifying the next-hop IP and the `track <id>` parameter.
The static route is created in conditional status linked to tracking object state.
Adding the `track` keyword instructs Cisco IOS to conditionally evaluate RIB placement.
4
Cisco IOS processes the UP status of the tracking object and writes the route to the routing table.
The default static route becomes active in the RIB with Administrative Distance 11.
RIB installation occurs only when the tracked object returns a valid UP reachability state.

Key Concept

IPv4 Static Route Object Tracking with IP SLA
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Topics

IPv4 Static Routing

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