On MikroTik routers using RouterOS, the administrative distance is a value that is assigned to routes obtained through different routing protocols to determine the preference of one route over another in case there are multiple routes to the same destination.

Administrative distance is a fundamental concept in routing as it helps avoid conflicts between routes and determines which route is considered the most reliable and therefore chosen for sending traffic.

OSPF Administrative Distance in MikroTik

For the OSPF (Open Shortest Path First) protocol in MikroTik, the default administrative distance is 110. This value is consistent with other network devices and adheres to industry standard practices, allowing for consistency and predictability in mixed network environments.

Why is administrative distance important?

Administrative distance is crucial when a router has multiple routes learned from different sources (e.g., static routes, OSPF, BGP) to the same destination.

The route with the lowest administrative distance has priority and is used to route traffic. Here are some common administrative distances to compare:

• Static routes: They generally have a distance of 1 (although this can be configured).
• EIGRP: Typically it has a distance of 90.
• OSPF: It has a distance of 110, as mentioned.
• BGP: Typically has a distance of 120 for internal routes.

Configuration and Adjustment of the Administrative Distance in MikroTik

In MikroTik RouterOS, you can adjust the administrative distance if necessary to tailor routing to your specific requirements. This can be done using the command line interface (CLI) or through WinBox or WebFig.

Here's how you could change the administrative distance for OSPF:

1. Access your MikroTik Router via WinBox or SSH.
2. Navigate to OSPF configuration:
   
   /routing ospf instance
   
3. Modify the administrative distance (only if it is necessary):
   
   set [find default=yes] distance=110
   
   This command checks if the default value is set and, if necessary, changes it.

Modifying the OSPF administrative distance can be useful in situations where you are integrating OSPF with other routing protocols and need to control which route takes precedence. However, such changes should be made with caution and with a full understanding of the implications on the global network.