300-710 SNCF Deployment Practice Question
An engineer is troubleshooting a passive NGIPS deployment where the Cisco Secure Firewall is connected to a switch SPAN port. Security analysts report that certain VLAN-tagged packets are not appearing in the event logs. What is the most likely cause?
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
✓
The passive interface or subinterfaces on the firewall are not configured to recognize or decode the specific 802.1Q VLAN tags present in the SPAN stream.
When monitoring trunk ports via SPAN, if the firewall's passive interface is configured without VLAN tagging enabled or lacks subinterfaces matching the trunk VLANs, tagged frames may be dropped or ignored.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The firewall management IP address is misconfigured, causing packet loss on the monitoring port.
Why it's wrong here
Management IP has no bearing on passive packet capture decoding.
- ✓
The passive interface or subinterfaces on the firewall are not configured to recognize or decode the specific 802.1Q VLAN tags present in the SPAN stream.
Why this is correct
If VLAN tags are present in the SPAN traffic, the passive interface must be configured to handle those VLANs to inspect the encapsulated packets.
- ✗
The Snort inspection engine drops all SPAN traffic by default unless inline bypass mode is active.
Why it's wrong here
Snort inspects SPAN traffic perfectly fine without inline bypass.
- ✗
Passive interfaces do not support VLAN tagging; all trunk traffic must be untagged at the switch SPAN source.
Why it's wrong here
Passive interfaces support VLAN tags if properly configured.
Visual reference
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official Cisco exam blueprint
This 300-710 SNCF 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 300-710 SNCF exam.