Quick Answer
The answer is 10 seconds. This is the default keepalive interval for a GRE tunnel interface on Cisco IOS-XE, defined by the `keepalive` command’s default behavior, which sends periodic keepalive packets to verify reachability of the tunnel destination. If no reply is received within three consecutive intervals—totaling 30 seconds by default—the tunnel interface is marked as down. On the Cisco CCNP ENARSI 300-410 exam, this concept tests your understanding of tunnel interface failure detection and the default timers that govern GRE keepalive behavior. A common trap is confusing the interval (10 seconds) with the retry count or the total down-detection time; remember that three missed replies trigger the down state, not a single missed interval. For a quick memory tip, think “10 seconds to send, 30 seconds to end”—the interval is a single digit, and the failure threshold is triple that.
This 300-410 practice question tests your understanding of ipv6 tunneling techniques. 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.
What is the default keepalive interval for a GRE tunnel interface on Cisco IOS-XE?
5 seconds
Why wrong: 5 seconds is not the default; it is configurable but not default.
10 seconds
The default keepalive interval is 10 seconds.
15 seconds
Why wrong: 15 seconds is not the default for GRE tunnels.
20 seconds
Why wrong: 20 seconds is not the default; it may be used for other tunnel types.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
10 seconds
The default keepalive interval for a GRE tunnel interface on Cisco IOS-XE is 10 seconds. This is defined by the default behavior of the `keepalive` command on tunnel interfaces, which sends periodic keepalive packets to verify the reachability of the tunnel destination. If no keepalive reply is received within three consecutive intervals (30 seconds by default), the tunnel interface is marked as down.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
5 seconds
Why it's wrong here
5 seconds is not the default; it is configurable but not default.
10 seconds
Why this is correct
The default keepalive interval is 10 seconds.
Related concept
Read the scenario before looking for a memorised answer.
15 seconds
Why it's wrong here
15 seconds is not the default for GRE tunnels.
20 seconds
Why it's wrong here
20 seconds is not the default; it may be used for other tunnel types.
Common exam traps
Cisco often tests the default keepalive interval for GRE tunnels, and the trap here is that candidates confuse it with the default keepalive interval for other interface types (e.g., serial interfaces default to 10 seconds as well, but some assume 5 or 15 seconds based on unrelated protocols like EIGRP hello timers).
Detailed technical explanation
The keepalive mechanism on GRE tunnels uses a simple echo/reply protocol encapsulated within the tunnel itself. The `keepalive` command can be configured with a custom interval and retry count; for example, `keepalive 5 3` sets a 5-second interval with 3 retries. In real-world scenarios, adjusting the keepalive interval is critical for fast convergence in MPLS or DMVPN deployments where tunnel stability directly impacts routing protocol adjacencies.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
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FAQ
IPv6 Tunneling Techniques — This question tests IPv6 Tunneling Techniques — Read the scenario before looking for a memorised answer..
The correct answer is: 10 seconds — The default keepalive interval for a GRE tunnel interface on Cisco IOS-XE is 10 seconds. This is defined by the default behavior of the `keepalive` command on tunnel interfaces, which sends periodic keepalive packets to verify the reachability of the tunnel destination. If no keepalive reply is received within three consecutive intervals (30 seconds by default), the tunnel interface is marked as down.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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