300-410 VPN Technologies Practice Question
A network engineer is deploying a site-to-site VPN between two Cisco IOS routers. The security policy requires that the peer identities be authenticated with certificates issued by an internal CA, and that the two peers negotiate a fresh keying channel for each new IKEv2 SA without relying on aggressive-mode pre-shared keys. Which IKEv2 configuration element must be present on both routers to satisfy the certificate-based authentication requirement?
⚠ Common exam trap
The trap here is assuming that because IKEv2 supports pre-shared keys, any IKEv2 authentication command satisfies a certificate requirement, when rsa-sig is what actually binds the profile to PKI credentials.
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
✓
crypto ikev2 profile with authentication remote rsa-sig and authentication local rsa-sig
Certificate-based IKEv2 authentication requires the IKEv2 profile to reference a PKI trustpoint and to specify rsa-sig for both local and remote authentication. The trustpoint supplies the CA chain and the router's own identity certificate, and rsa-sig makes the router present and verify X.509 signatures during the IKE_AUTH exchange. Pre-shared-key constructs, whether IKEv1 policies or IKEv2 keyrings, cannot meet a policy that mandates CA-issued certificates.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
crypto isakmp policy with authentication pre-share and a matching keyring
Why it's wrong here
The crypto isakmp policy with authentication pre-share belongs to IKEv1 and explicitly uses pre-shared keys, which the stated security policy forbids. Even though ISAKMP-style syntax still exists for backward compatibility, it cannot deliver the certificate-based peer authentication that the scenario demands, and it does not govern IKEv2 negotiation.
- ✓
crypto ikev2 profile with authentication remote rsa-sig and authentication local rsa-sig
Why this is correct
Under the IKEv2 profile, the authentication local rsa-sig and authentication remote rsa-sig commands instruct the router to use RSA signatures backed by X.509 certificates for both its own identity and the peer's identity. Combined with a pki trustpoint referencing the internal CA, this satisfies the certificate-authentication policy and avoids pre-shared keys entirely.
- ✗
crypto pki server with grant auto and a registered local RSA keypair
Why it's wrong here
The crypto pki server command configures the router to act as the CA itself, not to authenticate as a certificate-bearing peer. Granting automatic enrollment on the CA does not configure the IKEv2 profile to present or validate RSA signatures, so the IKEv2 peer authentication would still default to pre-shared keys and fail the policy.
- ✗
crypto ikev2 keyring with a peer entry containing an RSA public key
Why it's wrong here
An IKEv2 keyring holds pre-shared keys for peer authentication, not certificates. While the keyring syntax does allow an rsa-pubkey reference in some platforms, the keyring is fundamentally the pre-shared-key mechanism. Relying on it would not provide the CA-issued certificate authentication the policy requires for both peers.
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.
Go deeper
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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.