300-710 SNCF Practice Question: An administrator is configuring a Network Address Translation (NAT) rule on a Cisco FMC…
An administrator is configuring a Network Address Translation (NAT) rule on a Cisco FMC managed Threat Defense device. The requirement is to translate the source IP address of traffic coming from the inside zone going to the outside zone, but only for a specific internal subnet. Which NAT type must the administrator select in the FMC NAT rule configuration?
⚠ Common exam trap
Many exam-takers confuse Auto NAT with Manual NAT, as candidates may think Manual NAT is always required for subnet translation, but Auto NAT is specifically designed for object-based source translation.
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
✓
Auto NAT (Object NAT)
Auto NAT (Object NAT) in Cisco FMC is used to translate the source IP address of traffic for a specific object (such as an internal subnet) when it matches the specified conditions. It is configured within the object definition and is the simplest way to perform source NAT for a given subnet. Manual NAT is used for more complex scenarios, such as when both source and destination translation are needed or when NAT rules must be ordered.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Twice NAT (Destination NAT)
Why it's wrong here
Twice NAT, also called manual NAT, can translate source, destination or both, and is used when translation depends on the destination, for example policy NAT or overlapping networks. Translating only the destination, as this option describes, does not meet the requirement, which is to translate the source addresses of one internal subnet. Plain source translation for one subnet is exactly what auto NAT on a network object is designed for.
- ✗
Prefilter NAT
Why it's wrong here
There is no 'Prefilter NAT' type in Cisco Secure Firewall Threat Defense. Prefilter policies are a separate feature that decides early whether traffic is fast-pathed, blocked or passed on to full inspection, and they do not translate addresses. NAT rules are either auto NAT, defined on a network object, or manual NAT, and for one subnet's source translation, auto NAT is the right choice.
- ✓
Auto NAT (Object NAT)
Why this is correct
Auto NAT, or object NAT, is defined on a single network object, here the internal subnet, and translates only that object's source address between the chosen interfaces or zones. For outbound internet access it is usually dynamic PAT to the outside interface address. It is the simplest and recommended way to do ordinary source NAT, while manual NAT is reserved for translations that depend on the destination or need precise ordering.
- ✗
Manual NAT (Identity NAT)
Why it's wrong here
Identity NAT translates an address to itself, so the internal subnet's traffic would leave with its real addresses unchanged. It is used to exempt traffic from other NAT rules, most commonly site-to-site VPN traffic that must keep its original addresses. The requirement here is to translate the source addresses, so identity NAT does the opposite of what is needed.
Visual reference
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Written and reviewed by Johnson Ajibi, MSc IT Security
Security Systems Architect · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 300-710 SNCF 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 300-710 SNCF exam.