350-601 Security Practice Question
A data center engineer is troubleshooting connectivity issues between two EPGs in the same tenant on a Cisco ACI fabric. The first EPG 'web_epg' is in VLAN 100 and the second EPG 'db_epg' is in VLAN 200. The contract 'web_to_db' allows TCP port 3306 from web_epg to db_epg. The EPGs are in the same VRF. The engineer has verified that the physical connectivity is correct and the endpoints are learning their IP addresses. However, traffic from web_epg to db_epg is not reaching the destination. The engineer checks the contract and sees that the subject 'mysql_access' has filter 'mysql' with direction 'both'. The provider is db_epg and consumer is web_epg. The engineer also notices that the default action in the contract is 'deny'. What is the most likely cause of the issue?
⚠ Common exam trap
Cisco often tests the provider/consumer directionality in ACI contracts, and the trap here is that candidates assume the provider is the source (initiator) of traffic, when in fact the provider is the destination (service offerer).
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 contract direction is reversed: the provider should be the destination of the traffic. Since web_epg initiates to db_epg, web_epg should be the provider.
In Cisco ACI, the provider EPG is the one that offers a service (the destination of the traffic), and the consumer EPG is the one that initiates the connection. Since web_epg initiates TCP traffic to db_epg, db_epg should be the provider and web_epg the consumer. The contract is reversed, so the default deny action blocks the traffic because the consumer (web_epg) is not allowed to initiate toward the provider (db_epg) under the reversed roles.
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 contract direction is reversed: the provider should be the destination of the traffic. Since web_epg initiates to db_epg, web_epg should be the provider.
Why this is correct
In ACI, the provider offers a service; the consumer initiates. Here web_epg initiates, so web_epg should be provider.
- ✗
The VRF is not correctly associated with the EPGs.
Why it's wrong here
EPGs are in the same VRF, so routing is fine.
- ✗
A Layer 3 Outside (L3Out) is required for communication between EPGs in the same VRF.
Why it's wrong here
L3Out is for external connectivity, not internal EPG communication.
- ✗
The filter 'mysql' does not match TCP port 3306.
Why it's wrong here
The filter likely matches 3306, given it's named mysql.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-601 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 350-601 exam.