The correct answer is that DHCP snooping must be enabled on the VLAN and the port must be untrusted. This is because IP Source Guard relies entirely on the DHCP snooping binding table to map valid source IP addresses to MAC addresses on a per-port basis; without DHCP snooping populating that table, the switch has no reference to enforce against spoofed packets. On the Cisco DCCOR 350-601 exam, this dependency is a frequent trap—candidates often forget that enabling IP Source Guard alone does nothing unless DHCP snooping is active on the same VLAN and the client-facing port is marked as untrusted. The exam tests your understanding that IP Source Guard is a downstream enforcement mechanism, not a standalone feature. A solid memory tip is “No snoop, no guard”—if DHCP snooping isn’t building the binding table, IP Source Guard has no filter to apply.
350-601 Security Practice Question
This 350-601 practice question tests your understanding of security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network administrator wants to prevent IP spoofing attacks on a data center access switch. The switch has IP Source Guard enabled on the client-facing ports. Which condition must be met for IP Source Guard to work properly?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
DHCP snooping must be enabled on the VLAN and the port must be untrusted.
IP Source Guard uses a binding table created by DHCP snooping to validate the source IP address of packets received on a port. For IP Source Guard to work, DHCP snooping must be enabled on the VLAN, and the client-facing port must be configured as an untrusted port so that DHCP snooping can populate the binding table with valid DHCP lease information. Without this binding table, IP Source Guard has no source IP-to-MAC mapping to enforce.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
DHCP snooping must be disabled on the VLAN.
Why it's wrong here
IP Source Guard requires DHCP snooping to populate the binding table.
✓
DHCP snooping must be enabled on the VLAN and the port must be untrusted.
Why this is correct
IP Source Guard uses the DHCP snooping binding table on untrusted ports.
Related concept
Read the scenario before looking for a memorised answer.
✗
All clients must use DHCP; static IPs are not supported.
DAR is separate but often used together, not a prerequisite.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the dependency between IP Source Guard and DHCP snooping, specifically that DHCP snooping must be enabled on the VLAN and the port must be untrusted, leading candidates to incorrectly assume DHCP snooping must be disabled or that static IPs are unsupported.
Detailed technical explanation
How to think about this question
IP Source Guard operates by comparing the source IP and MAC of incoming packets against the DHCP snooping binding table, which is built from DHCP ACK messages intercepted on untrusted ports. On a trusted port (e.g., uplink to a DHCP server), DHCP snooping does not create bindings, so IP Source Guard would have no entries to validate against, effectively blocking all traffic. In a real-world scenario, if an administrator mistakenly sets a client port as trusted, IP Source Guard cannot prevent spoofing because the binding table remains empty for that port.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: DHCP snooping must be enabled on the VLAN and the port must be untrusted. — IP Source Guard uses a binding table created by DHCP snooping to validate the source IP address of packets received on a port. For IP Source Guard to work, DHCP snooping must be enabled on the VLAN, and the client-facing port must be configured as an untrusted port so that DHCP snooping can populate the binding table with valid DHCP lease information. Without this binding table, IP Source Guard has no source IP-to-MAC mapping to enforce.
What should I do if I get this 350-601 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An attacker attempts to spoof a legitimate client's IP address to intercept traffic. DHCP snooping is enabled. Which feature prevents this spoofing by validating source IP in data packets?
hard
A.Port security
✓ B.IP Source Guard
C.Dynamic ARP Inspection
D.DHCP Snooping binding database
Why B: IP Source Guard (IPSG) uses the DHCP snooping binding database to validate the source IP address in data packets received on untrusted ports. If a packet's source IP does not match an entry in the binding table, IPSG drops the packet, preventing IP spoofing attacks.
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Question Discussion
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