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 network with asymmetric routing. Users report intermittent connectivity issues. Which is the most likely explanation?
⚠ Common exam trap
Cisco often tests the misconception that uRPF drops packets only when there is no route for the source IP, but the real trap is that strict mode requires the reverse path to use the exact same interface, which fails under asymmetric routing even when a valid route exists.
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 packets to arrive on an interface that is not the best return path, so uRPF drops them.
Unicast Reverse Path Forwarding (uRPF) in strict mode checks that the source IP address of an incoming packet has a route in the routing table pointing back out the same interface on which the packet arrived. In an asymmetric routing scenario, packets may arrive on an interface that is not the best return path, causing the uRPF check to fail and the packet to be dropped. This explains the intermittent connectivity issues reported by users.
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 packets to arrive on an interface that is not the best return path, so uRPF drops them.
Why this is correct
Correct. Strict mode requires symmetric routing.
- ✗
The uRPF configuration is missing the 'allow-default' option.
Why it's wrong here
Allow-default is for loose mode, not strict.
- ✗
The routing table does not have a route for the source IP.
Why it's wrong here
If no route, uRPF would drop all packets, not intermittent.
- ✗
The interface has multiple IP addresses.
Why it's wrong here
Multiple IPs do not cause uRPF issues.
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.