350-501 Security and Services Practice Question
An SP is implementing Carrier-Grade NAT (CGNAT) to conserve IPv4 addresses. Which feature must be enabled to support applications that embed IP addresses in the payload, such as SIP or FTP?
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
✓
ALG (Application Layer Gateway)
Application Layer Gateway (ALG) is required to inspect and modify payloads for protocols like SIP and FTP that carry IP addresses in the data stream.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
IPSec
Why it's wrong here
IPSec is for encryption, not NAT traversal of embedded addresses.
- ✗
Port forwarding
Why it's wrong here
Port forwarding is a static mapping, not for dynamic payload inspection.
- ✓
ALG (Application Layer Gateway)
Why this is correct
ALG handles payload inspection for protocols that embed IP addresses.
- ✗
NAT traversal
Why it's wrong here
NAT traversal is for IPSec, not general ALG functionality.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-501 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 350-501 exam.