OSPF vs Static Route Preference via Administrative Distance
Short answer
C Adjust the administrative distance so the static route's value is higher than OSPF's 110, making the OSPF-learned route preferred.
Question
Key Takeaways
This question tests that AD is compared before metric across route sources, and that a default static route (AD 1) beats internal OSPF (AD 110) unless AD is adjusted.
Administrative distance is the tiebreaker between an OSPF-learned route and a static route; adjusting it so the static route's AD is higher than OSPF's makes OSPF preferred (C).
Common mistake: A tempting wrong answer is A: adding the ISP as an OSPF neighbor may add external OSPF routes, but it does not change the AD comparison, so the local static route still wins over the OSPF route.
Expert Analysis
Route selection order matters. When a router has more than one source for the same destination, it does not immediately compare OSPF cost against a static route metric. It first chooses the longest matching prefix; if two candidates have the same prefix length but come from different route sources, it compares administrative distance (AD). AD is a local trustworthiness value, and lower is better. Only routes from the same protocol or same AD are then compared by metric. Here, the static route defaults to AD 1 and internal OSPF to AD 110, so the static route would normally be installed and the OSPF route hidden.
What actually flips preference. To ensure the OSPF-learned route wins, change the AD relationship: raise the static route's AD above 110, commonly to a floating-static value such as 115, or lower OSPF's AD below the static route's AD. Then OSPF is selected while it exists, and the static route remains a backup that can be installed if OSPF withdraws. The supplied comment captures this mechanism accurately: static is AD 1, OSPF internal is 110, lower AD wins, and AD must be adjusted to prefer OSPF.
Why the other options fail. Option A, adding the ISP router as an OSPF neighbor, may add OSPF routes but does not change the local AD comparison for this prefix. Option B, enabling FHRP, provides default-gateway redundancy and has nothing to do with route-source preference. Option D, changing to EIGRP, replaces the routing protocol and does not make an OSPF-learned route preferred; it also changes AD and metric behavior wholesale.
The correct choice. Option C, adjust the administrative distance, is the only setting that directly resolves the static-versus-OSPF conflict. A useful exam phrase is "floating static route": set its AD higher than the dynamic protocol so the dynamic route is preferred normally and the static route is used as a fallback.
Official Reference
https://www.comptia.org/certifications/network
This link opens the official vendor documentation in a new tab.
Exam Strategy
When a question mixes a dynamic protocol and a static route for the same destination, first check the prefix length; if it is equal, compare administrative distance before metric. Static routes usually have AD 1 and OSPF 110, so any answer that does not change AD or the route source is unlikely to flip preference. Look for "floating static" wording: a static route with AD above OSPF is a backup, not the preferred path.
Frequently Asked Questions
Why does a static route usually beat an OSPF route even when OSPF has a better metric?
How do you make a static route a backup for OSPF?
Does adding the ISP router as an OSPF neighbor change administrative distance?
Discussion 1 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 1
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ERB14 👍 1 Answered CAdministrative Distance (AD): By default, a static route has an Administrative Distance of 1, while OSPF has an AD of 110 (for OSPF internal routes). Because lower AD values are preferred by the router, a newly added static route would normally override the OSPF-learned route. Ensuring OSPF is Preferred: To make the router prefer the OSPF-learned route over the static route, you must adjust the administrative distance of the static route to a higher value than OSPF's AD (e.g., setting the static route's AD to 115 or higher).
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