hardMultiple ChoiceObjective-mapped
How to Interpret NAT Translation Table with PAT and Static
A network engineer runs the following command on Router R9:
R9# show ip nat translations
Pro Inside global Inside local Outside local Outside global udp 192.0.2.20:1234 10.0.0.20:1234 203.0.113.1:53 203.0.113.1:53 tcp 192.0.2.20:5678 10.0.0.20:5678 198.51.100.1:80 198.51.100.1:80 --- 192.0.2.21 10.0.0.21 --- ---
Based on this output, what can be concluded?
Quick Answer
The answer is that the router is using both static NAT and PAT simultaneously. This conclusion is drawn directly from the NAT translation table output, which shows two distinct translation types: the first two entries include protocol (udp, tcp) and port numbers (1234, 5678), indicating dynamic PAT where multiple inside local addresses share a single inside global address through port multiplexing, while the third entry has no protocol or port, with a simple one-to-one mapping from 10.0.0.21 to 192.0.2.21, which is the hallmark of a static NAT configuration. On the ENCOR 350-401 exam, this question tests your ability to read and interpret the show ip nat translations output, a common troubleshooting skill, and often appears as a trap where candidates mistakenly think all entries are PAT because they see ports, missing the static entry. A key memory tip: if you see a protocol and port in the first column, it is PAT; if you see three dashes, it is static or dynamic NAT without overload.
⚠ Common exam trap
Cisco often tests the distinction between static NAT (no ports) and dynamic PAT (with ports) in the 'show ip nat translations' output, leading candidates to mistakenly think all entries are dynamic when they see multiple translations sharing the same inside global address.
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
✓
The router is using both static NAT and PAT simultaneously.
The output shows two types of NAT entries: a dynamic PAT entry for UDP (192.0.2.20:1234) and TCP (192.0.2.20:5678), and a static one-to-one translation for 192.0.2.21 to 10.0.0.21 (indicated by '---' in the protocol and port fields). This combination of dynamic PAT and static NAT on the same router confirms that both static NAT and PAT are being used simultaneously.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
All translations are dynamic.
Why it's wrong here
The third entry has no protocol, indicating it is static.
- ✓
The router is using both static NAT and PAT simultaneously.
Why this is correct
Static NAT for 10.0.0.21 and PAT for 10.0.0.20 are both active.
- ✗
The router is configured with a single NAT pool.
Why it's wrong here
Static NAT does not use a pool; PAT may use a pool or interface.
- ✗
The inside global address 192.0.2.20 is used for both static and dynamic translations.
Why it's wrong here
192.0.2.20 is used only for dynamic PAT; static uses 192.0.2.21.
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Same concept, more angles
1 more way 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. A network engineer runs the following command on Router R5: R5# show ip nat translations Pro Inside global Inside local Outside local Outside global udp 192.0.2.20:1234 10.0.0.20:1234 203.0.113.1:53 203.0.113.1:53 tcp 192.0.2.20:5678 10.0.0.20:5678 198.51.100.1:80 198.51.100.1:80 Based on this output, what can be concluded?
hard- A.The router is configured with static NAT for two internal hosts.
- ✓ B.The router is performing Port Address Translation (PAT) for multiple sessions from the same internal host.
- C.The router is performing destination NAT.
- D.The inside local address 10.0.0.20 is using two different global addresses.
Why B: The output shows two different translations (UDP and TCP) for the same inside local address 10.0.0.20, both using the same inside global address 192.0.2.20 but with different port numbers (1234 and 5678). This is characteristic of Port Address Translation (PAT), also known as NAT overload, where a single public IP address is shared among multiple sessions from the same internal host by multiplexing on the transport layer port. Option B correctly identifies this behavior.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 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 350-401 exam.