Question 544 of 1,958
mediumMultiple ChoiceObjective-mapped
Why IKEv2 Profile Needs a Proposal/Policy for Pre-Shared Key VPN
Given this configuration on a Cisco IOS-XE router:
crypto ikev2 keyring KEYRING
peer SPOKE1 address 192.168.2.1 pre-shared-key cisco123 !
crypto ikev2 profile IKEV2_PROF
match identity remote address 192.168.2.1 255.255.255.255 authentication remote pre-share authentication local pre-share keyring KEYRING !
What is missing from this configuration for a successful IKEv2 tunnel to the peer at 192.168.2.1?
Quick Answer
The answer is that the IKEv2 proposal and policy are missing and must be referenced by the profile. Without a defined IKEv2 proposal specifying encryption, integrity, and Diffie-Hellman group parameters, and a policy that links those parameters to the profile, the router has no cryptographic framework to negotiate with the peer. The keyring and authentication methods are correctly configured, but IKEv2 cannot establish Phase 1 without a proposal-policy pairing. On the ENCOR 350-401 exam, this is a classic trap: candidates see a pre-shared key and authentication commands and assume the tunnel is complete, forgetting that IKEv2 requires an explicit proposal and policy to be either applied directly to the profile or inherited from a global policy. The exam tests your understanding that IKEv2 negotiation is a two-step process—first the proposal/policy, then the authentication. Memory tip: think “Proposal first, policy second, profile third”—without the first two, the third has nothing to negotiate.
⚠ Common exam trap
Cisco often tests the distinction between IKEv1 and IKEv2 configuration requirements, and the trap here is that candidates assume an IKEv2 profile alone is sufficient, forgetting that IKEv2 still requires explicit proposal and policy definitions.
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 IKEv2 proposal and policy are not defined and must be referenced by the profile or the IPsec profile.
The configuration is missing an IKEv2 proposal and an IKEv2 policy, which define the encryption, integrity, and DH group parameters for the IKEv2 SA. The profile must reference these via the 'proposal' command under the IKEv2 proposal or the 'match proposal' command under the IKEv2 policy; without them, the router has no agreed-upon parameters to negotiate with the peer, so the tunnel cannot be established.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The configuration is complete; no additional commands are needed.
Why it's wrong here
The IKEv2 proposal and policy are missing. The profile references the keyring but does not define the encryption/integrity parameters.
- ✗
The profile is missing the 'set transform-set' command to specify the IPsec transform set.
Why it's wrong here
The transform set is part of the IPsec profile, not the IKEv2 profile. The IKEv2 profile is for phase 1; the transform set is for phase 2.
- ✓
The IKEv2 proposal and policy are not defined and must be referenced by the profile or the IPsec profile.
Why this is correct
IKEv2 requires a proposal (encryption, integrity, DH group) and a policy to associate the proposal with the profile. Without these, the IKEv2 negotiation will fail.
- ✗
The keyring must use a different name to match the profile.
Why it's wrong here
The keyring name is correctly referenced in the profile with the 'keyring' command.
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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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. An engineer is configuring a site-to-site VPN between two Cisco routers using IPsec with IKEv2. The engineer wants to use a pre-shared key. The configuration on both routers includes: crypto ikev2 proposal default, encryption aes-cbc-256, integrity sha256, group 14. The engineer also configures crypto ikev2 keyring and crypto ikev2 profile. The tunnel does not establish. The engineer sees that the IKEv2 SA is not created. What is the most likely missing configuration?
hard- A.The IKEv2 proposal is not configured correctly.
- ✓ B.The IKEv2 profile is not attached to the crypto map or interface.
- C.The IPsec transform set is missing.
- D.The pre-shared key is not defined in the keyring.
Why B: The IKEv2 profile must be attached to a crypto map or directly to an interface (using 'crypto ikev2 profile' under the crypto map or 'tunnel protection ipsec profile') to be used during IKEv2 negotiation. Without this attachment, the router does not know which profile (and thus which keyring and pre-shared key) to apply, so the IKEv2 SA never forms.
Last reviewed: Jul 4, 2026
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