Question 1,148 of 2,011
hardMultiple ChoiceObjective-mapped
300-410 Practice Question: An engineer configures unicast Reverse Path…
An engineer configures unicast Reverse Path Forwarding (uRPF) in strict mode on an interface connected to a customer network. The customer has a default route pointing to the router. After enabling uRPF, the router drops traffic from the customer that has a source IP address that is not in the routing table as a directly connected or static route. What is the most likely explanation?
⚠ Common exam trap
Cisco often tests the misconception that a default route satisfies strict mode uRPF requirements, but the trap is that strict mode demands a specific route (not a default) for the source IP, and the incoming interface must match the route's outgoing interface.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Strict mode uRPF requires a specific route for the source IP; a default route is not sufficient.
Strict mode uRPF verifies that the source IP address of an incoming packet matches a specific route in the routing table, and that the interface used to reach that source IP is the same as the incoming interface. A default route (0.0.0.0/0) is a catch-all entry and does not provide a specific, directly connected or static route for the customer's source IP. Therefore, the router drops the traffic because it cannot find an exact match for the source IP in the routing table, which is a fundamental requirement of strict mode.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Strict mode uRPF requires a specific route for the source IP; a default route is not sufficient.
Why this is correct
Strict mode checks for a matching route with the same incoming interface; a default route does not provide a specific interface match.
- ✗
The customer's default route causes asymmetric routing, which breaks strict mode.
Why it's wrong here
Asymmetric routing is a problem for strict mode, but the issue here is missing route for the source IP.
- ✗
The uRPF mode should be loose mode to allow the default route.
Why it's wrong here
Loose mode only checks that a route exists, not the interface, but the question specifies strict mode.
- ✗
The router has an ACL that is blocking the traffic before uRPF checks.
Why it's wrong here
uRPF is applied before ACLs, so ACL is not the cause.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 24, 2026
This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.