hardMultiple ChoiceObjective-mapped
300-410 Practice Question: An engineer configures uRPF (Unicast Reverse Path…
An engineer configures uRPF (Unicast Reverse Path Forwarding) in strict mode on a router interface facing the Internet. After configuration, legitimate traffic from customers is being dropped. The engineer verifies that the routing table has a route back to the source IP address. Which is the most likely explanation?
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
✓
Asymmetric routing causes the return path to use a different interface
Strict uRPF checks that the source IP address of incoming packets has a route back through the same interface. If asymmetric routing is present (i.e., traffic comes in one interface but the return route points out a different interface), strict uRPF will drop the packets. This is a common edge case because engineers often assume that having a route to the source is sufficient, but strict mode requires the reverse path to be via the same interface.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Asymmetric routing causes the return path to use a different interface
Why this is correct
Correct. Strict uRPF drops packets if the best return route does not exit the same interface.
- ✗
The uRPF allow-default option is not configured
Why it's wrong here
The allow-default option only affects default routes, not asymmetric routing.
- ✗
The source IP address is not in the routing table
Why it's wrong here
The engineer verified that the route exists.
- ✗
uRPF strict mode requires CEF to be disabled
Why it's wrong here
uRPF requires CEF to be enabled.
Quick reference
Asymmetric Encryption Algorithm Comparison
| Algorithm | Key Exchange | Signatures | Equivalent Security Key | Notes |
|---|---|---|---|---|
| RSA-3072 | Yes | Yes | 128-bit | Widely deployed; slow for bulk data |
| ECDSA P-256 | No | Yes | 128-bit | Fast signatures; standard TLS certs |
| ECDH / ECDHE | Yes | No | 128-bit | Perfect forward secrecy in TLS 1.3 |
| DH / DHE | Yes | No | 128-bit (3072-bit key) | Replaced by ECDHE in modern TLS |
| Ed25519 | No | Yes | ~128-bit | SSH keys, modern PKI |
Go deeper
Related to this question
About these practice questions
Courseiva writes every 300-410 question from scratch — 1,966 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.