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300-410 Practice Question: In IPsec site-to-site VPN, what is the default…
In IPsec site-to-site VPN, what is the default lifetime for ISAKMP (IKE phase 1) security associations on Cisco IOS routers?
⚠ Common exam trap
Cisco often tests the distinction between IKE phase 1 and IPsec phase 2 default lifetimes, so the trap here is confusing the 86400-second (24-hour) default for ISAKMP with the 3600-second (1-hour) default for IPsec SAs.
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 (24 hours)
The default lifetime for ISAKMP (IKE phase 1) security associations on Cisco IOS routers is 86400 seconds (24 hours). This is defined in the Cisco IOS default configuration for the `crypto isakmp policy` and is the recommended value to balance security and performance by reducing the frequency of re-authentication and Diffie-Hellman key exchanges.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
3600 seconds (1 hour)
Why it's wrong here
3600 seconds is the default for IPsec (phase 2) SA, not ISAKMP.
- ✓
86400 seconds (24 hours)
Why this is correct
This is the Cisco default for ISAKMP lifetime.
- ✗
28800 seconds (8 hours)
Why it's wrong here
This is not a standard default; 86400 is the correct value.
- ✗
1800 seconds (30 minutes)
Why it's wrong here
This is too short and not the default.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
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JA
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.