- A
60 seconds
Why wrong: This is the default for UDP, not TCP.
- B
300 seconds
Why wrong: This is not the default TCP timeout in Cisco IOS.
- C
3600 seconds
Why wrong: This is the timeout for an established TCP session after the first packet, but the default idle timeout is 86400 seconds.
- D
86400 seconds
Correct. The default TCP NAT translation timeout is 24 hours (86400 seconds) in Cisco IOS.
Question 1,624 of 2,152
300-410 NAT and PAT Practice Question
This 300-410 practice question tests your understanding of nat and pat. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
In Cisco IOS, what is the default timeout for TCP NAT translations when the TCP session is idle?
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
✓
86400 seconds
The correct answer is D (86400 seconds) because Cisco IOS defaults TCP NAT translation timeouts for idle sessions to 24 hours (86400 seconds). This long timeout ensures that established TCP sessions are not prematurely dropped by the NAT device, preserving connectivity for long-lived connections such as database replication or SSH sessions. The timeout is configurable via the 'ip nat translation timeout' command, but the default remains 86400 seconds.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between the default timeout for idle TCP sessions (86400 seconds) versus the timeout after TCP session teardown (3600 seconds), leading candidates to confuse the two and select 3600 seconds.
Detailed technical explanation
How to think about this question
Under the hood, Cisco IOS maintains a NAT translation table where each entry has a timer that resets on packet activity. For TCP, the default idle timeout of 86400 seconds is deliberately long to avoid breaking TCP connections that may have long periods of silence (e.g., keepalive intervals). In real-world scenarios, if an administrator mistakenly reduces this timeout to 3600 seconds, long-running database or backup sessions may be disrupted, causing application timeouts and retransmissions.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Visual reference
What to study next
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FAQ
Questions learners often ask
What does this 300-410 question test?
NAT and PAT — This question tests NAT and PAT — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 86400 seconds — The correct answer is D (86400 seconds) because Cisco IOS defaults TCP NAT translation timeouts for idle sessions to 24 hours (86400 seconds). This long timeout ensures that established TCP sessions are not prematurely dropped by the NAT device, preserving connectivity for long-lived connections such as database replication or SSH sessions. The timeout is configurable via the 'ip nat translation timeout' command, but the default remains 86400 seconds.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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