300-410 VPN Technologies Practice Question
A network engineer is deploying a GET VPN solution using Cisco IOS routers. The key server must be configured to rekey group members. Which protocol does GET VPN use to distribute encryption keys and policies to group members?
⚠ Common exam trap
It's easy for candidates to confuse IKEv2, which is used for point-to-point IPsec, with GDOI, which is specifically for group key management in GET VPN.
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
✓
Group Domain of Interpretation (GDOI)
GET VPN uses the Group Domain of Interpretation (GDOI) protocol to distribute encryption keys and policies from the key server to group members. GDOI enables scalable group key management, allowing the key server to send rekey messages to all members. IKEv2 is for point-to-point VPNs, and the other options are not used for GET VPN key distribution.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Group Domain of Interpretation (GDOI)
Why this is correct
GDOI is the protocol used by GET VPN to distribute encryption keys and policies from the key server to group members. It operates over UDP port 848 and allows the key server to push rekey messages, ensuring all group members share the same security policy and keys. GDOI is essential for the scalable any-to-any communication that GET VPN provides.
- ✗
Group Key Management Protocol (GKMP)
Why it's wrong here
GKMP is an older group key management protocol that was not widely adopted and is not used by Cisco GET VPN. GET VPN specifically uses GDOI for group key and policy distribution. While GKMP shares some concepts, it lacks the features and support needed for GET VPN deployments, so it is not the correct choice here.
- ✗
Multicast Group Management Protocol (MGMP)
Why it's wrong here
MGMP is not a real protocol for key management; it appears to be a distractor. GET VPN uses GDOI for group key distribution. MGMP might be confused with multicast group management protocols like IGMP, but those are for multicast group membership, not encryption key distribution. Thus, MGMP is not applicable for GET VPN rekeying.
- ✗
Internet Key Exchange version 2 (IKEv2)
Why it's wrong here
IKEv2 is used for point-to-point IPsec VPNs to negotiate security associations between two peers. While IKEv2 can be used for unicast key exchange, it is not designed for group key management. GET VPN requires a group key management protocol that can efficiently distribute keys to many members, which IKEv2 does not provide. Therefore, IKEv2 is not used for rekeying in GET VPN.
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
Related to this question
Learn chapter
Device Management and Network Monitoring (SNMP, Syslog, NetFlow)
Key term
GET VPN
Group Encrypted Transport VPN is a Cisco technology that secures IP multicast and unicast traffic across a wide area network using a shared security association rather than point-to-point tunnels.
Key term
FlexVPN
FlexVPN is a Cisco VPN solution that combines multiple VPN technologies (site-to-site, remote access, and hub-and-spoke) under a single, modular framework based on IKEv2.
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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.