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300-410 Practice Question: Which TWO statements about NAT overload (PAT) are…
Which TWO statements about NAT overload (PAT) are true? (Choose TWO.)
⚠ Common exam trap
Cisco often tests the misconception that PAT requires a single public IP address or that it cannot handle protocols with fixed port numbers, when in fact PAT can use a pool of addresses and translates the source port regardless of the destination port.
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
✓
PAT allows multiple inside hosts to share a single public IP address by using unique source port numbers.
A is correct because PAT (Port Address Translation) allows multiple internal hosts to share a single public IP address by assigning unique source port numbers to each session. This multiplexing technique enables many concurrent connections from different inside hosts to appear as if they originate from the same public IP, with the NAT device tracking each session by the combination of source IP and source port.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
PAT allows multiple inside hosts to share a single public IP address by using unique source port numbers.
Why this is correct
PAT translates the source port to create a unique session identifier, enabling many hosts to share one global address.
- ✗
PAT is only supported with a single public IP address configured on the outside interface.
Why it's wrong here
PAT can be used with a pool of public IP addresses as well; it is not limited to a single address.
- ✓
PAT is also known as NAT overload and is defined in RFC 2663.
Why this is correct
PAT is commonly referred to as NAT overload and is documented in RFC 2663 (IP Network Address Translator Terminology).
- ✗
PAT cannot translate traffic for protocols that use static port numbers, such as DNS or HTTP.
Why it's wrong here
PAT can translate any TCP/UDP traffic, including DNS and HTTP; it only fails for protocols that embed IP addresses in the payload (e.g., FTP, SIP) unless ALG is used.
- ✗
PAT requires the ip nat inside source list command with the overload keyword.
Why it's wrong here
While the overload keyword is used in dynamic NAT, PAT can also be configured with ip nat inside source list ... interface ... overload; the statement is too narrow because PAT can also be configured with a pool.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 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 300-410 exam.