- A
IP Source Guard uses the DHCP snooping binding table to validate the source IP address of packets received on a port.
Correct because IPSG relies on the DHCP snooping database to determine allowed source IPs.
- B
IP Source Guard can be configured with port security to provide additional MAC address filtering.
Correct because IPSG and port security can be combined to enforce both IP and MAC address filtering.
- C
IP Source Guard only works with DHCP-assigned IP addresses, not static IP addresses.
Why wrong: Incorrect because static IP source bindings can be manually configured to support static IPs.
- D
IP Source Guard filters traffic based on the destination MAC address.
Why wrong: Incorrect because IPSG filters based on source IP address, not destination MAC.
- E
IP Source Guard requires 802.1X authentication to be enabled on the port.
Why wrong: Incorrect because IPSG can operate without 802.1X; it only needs DHCP snooping or static bindings.
Quick Answer
The correct answer is that IP Source Guard can be configured with port security to provide additional MAC address filtering. This is true because IP Source Guard (IPSG) filters IP traffic on untrusted Layer 2 ports by leveraging the DHCP snooping binding table or static bindings, while port security adds a separate layer of MAC address control, allowing both features to complement each other on access ports. On the ENCOR 350-401 exam, this tests your understanding of Layer 2 security mechanisms and their interoperability; a common trap is assuming IPSG filters at Layer 2 or requires 802.1X, but it actually operates at Layer 3 and works independently. Remember the memory tip: “IPSG guards the IP, port security guards the MAC—together they double-check the stack.”
350-401 Infrastructure Security Practice Question
This 350-401 practice question tests your understanding of infrastructure 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.
Which two statements about IP Source Guard are true? (Choose two.)
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
IP Source Guard uses the DHCP snooping binding table to validate the source IP address of packets received on a port.
IP Source Guard (IPSG) is a security feature that filters IP traffic on untrusted Layer 2 ports based on the DHCP snooping binding table or static IP source bindings. It can be configured with or without port security. IPSG is typically applied on access ports facing end devices. Option C is incorrect because IPSG can be used with both static and DHCP-assigned IP addresses. Option D is incorrect because IPSG filters traffic at Layer 3 (IP), not Layer 2. Option E is incorrect because IPSG does not require 802.1X authentication; it can operate independently.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
IP Source Guard uses the DHCP snooping binding table to validate the source IP address of packets received on a port.
Why this is correct
Correct because IPSG relies on the DHCP snooping database to determine allowed source IPs.
Related concept
Static NAT maps one inside address to one outside address.
- ✓
IP Source Guard can be configured with port security to provide additional MAC address filtering.
Why this is correct
Correct because IPSG and port security can be combined to enforce both IP and MAC address filtering.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
IP Source Guard only works with DHCP-assigned IP addresses, not static IP addresses.
Why it's wrong here
Incorrect because static IP source bindings can be manually configured to support static IPs.
- ✗
IP Source Guard filters traffic based on the destination MAC address.
Why it's wrong here
Incorrect because IPSG filters based on source IP address, not destination MAC.
- ✗
IP Source Guard requires 802.1X authentication to be enabled on the port.
Why it's wrong here
Incorrect because IPSG can operate without 802.1X; it only needs DHCP snooping or static bindings.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-401 NAT questions on configuration and troubleshooting.
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FAQ
Questions learners often ask
What does this 350-401 question test?
Infrastructure Security — This question tests Infrastructure Security — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: IP Source Guard uses the DHCP snooping binding table to validate the source IP address of packets received on a port. — IP Source Guard (IPSG) is a security feature that filters IP traffic on untrusted Layer 2 ports based on the DHCP snooping binding table or static IP source bindings. It can be configured with or without port security. IPSG is typically applied on access ports facing end devices. Option C is incorrect because IPSG can be used with both static and DHCP-assigned IP addresses. Option D is incorrect because IPSG filters traffic at Layer 3 (IP), not Layer 2. Option E is incorrect because IPSG does not require 802.1X authentication; it can operate independently.
What should I do if I get this 350-401 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-401 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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 →
Same concept, more angles
1 more ways this is tested on 350-401
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. Which two statements about IP Source Guard are true? (Choose two.)
medium- ✓ A.IP Source Guard uses the DHCP snooping binding database to validate source IP addresses.
- B.IP Source Guard filters traffic based on the source MAC address.
- C.IP Source Guard is applied on Layer 3 interfaces of a switch.
- ✓ D.IP Source Guard can be configured with a static IP source binding for hosts with static IP addresses.
- E.IP Source Guard requires 802.1X authentication to function.
Why A: IP Source Guard (IPSG) filters IP traffic on a per-port basis using the DHCP snooping binding database. Option A is correct because IPSG uses the binding database to validate source IP addresses. Option D is correct because IPSG can be configured with a static IP source binding for hosts with static IP addresses. Option B is incorrect because IPSG does not filter MAC addresses; that is the role of port security. Option C is incorrect because IPSG is applied on Layer 2 switch ports, not on Layer 3 interfaces. Option E is incorrect because IPSG does not require 802.1X; it can work with DHCP snooping alone.
Last reviewed: Jun 18, 2026
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