350-401 Security Practice Question
A network administrator is implementing Dynamic ARP Inspection (DAI) on a Cisco Catalyst switch. The network uses DHCP for most endpoints, but a few servers have static IP addresses. Which two actions are required to ensure DAI allows legitimate traffic while blocking ARP spoofing? (Choose two.)
⚠ Common exam trap
The trap here is forgetting that DAI depends on DHCP snooping bindings, so static hosts require an ARP ACL or they will be dropped.
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
✓
Configure static ARP ACLs for hosts with statically assigned IP addresses.
DAI validates ARP packets against the DHCP snooping binding table, so DHCP snooping must be enabled on the same VLANs. Static hosts are not in that table, so an ARP ACL must be configured to permit their specific IP-to-MAC bindings. Together, these actions allow legitimate DHCP and static traffic while blocking spoofed ARP packets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Configure static ARP ACLs for hosts with statically assigned IP addresses.
Why this is correct
Hosts with static IP addresses do not appear in the DHCP snooping binding table, so DAI would drop their ARP packets. Creating a static ARP ACL and applying it to the DAI configuration with the arp access-list command allows those specific IP-to-MAC mappings to be validated. This ensures legitimate static hosts are not blocked while spoofing remains prevented.
- ✗
Enable port security with sticky MAC addresses on all access ports.
Why it's wrong here
Port security limits the number of MAC addresses per port and can restrict which devices connect, but it does not validate ARP packets. DAI uses the DHCP snooping binding table and ARP ACLs, not port security, to determine whether an ARP packet is legitimate. Enabling port security does not address the static-host validation requirement.
- ✗
Configure DAI to trust all access ports.
Why it's wrong here
Configuring DAI to trust all access ports would bypass ARP inspection on those ports, defeating the purpose of DAI and allowing ARP spoofing. Trusted ports are typically uplinks toward other switches or routers, not access ports where endpoints connect. This would not allow legitimate static hosts to be validated; it would simply disable inspection.
- ✗
Disable IP Source Guard on all access ports.
Why it's wrong here
IP Source Guard is a separate feature that filters IP traffic based on the DHCP snooping binding table. Disabling it does not affect DAI validation and is not required for DAI to function. In fact, IP Source Guard can complement DAI, so turning it off would reduce protection without solving the static-host issue.
- ✓
Enable DHCP snooping on the VLANs where DAI is enabled.
Why this is correct
DAI relies on the DHCP snooping binding table to validate ARP packets. Without DHCP snooping enabled on the same VLANs, the binding table is empty and DAI will drop legitimate ARP traffic from DHCP clients. Enabling DHCP snooping builds the IP-to-MAC bindings that DAI uses to permit valid ARP packets and deny spoofed ones.
Visual reference
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
Related to this question
Learn chapter
SDN Controllers and Cisco ACI
Key term
L2 Security Features
L2 Security Features are network security mechanisms that operate at Layer 2 of the OSI model to protect local network traffic from threats like MAC spoofing, ARP attacks, and unauthorized access.
Key term
DHCP snooping
DHCP snooping is a network security feature that filters untrusted DHCP messages to prevent rogue DHCP servers from giving out false IP addresses.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 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 350-401 exam.