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Which two protocols are required for DMVPN? (Choose two)
A. IPsec
B. PPTP
C. mGRE
D. NHRP
E. Open VPN
Correct Answer: CD
Explanation/Reference:
Explanation:
The DMVPN feature allows users to better scale large and small IP Security (IPsec) Virtual Private Networks (VPNs) by combining generic routing encapsulation (GRE) tunnels, IPsec encryption, and Next Hop Resolution Protocol (NHRP).
http://www.cisco.com/c/en/us/td/docs/ios/12_4/ip_addr/configuration/guide/hadnhrp.html
DMVPN is not a protocol, it is the combination of the following technologies:
+ Multipoint GRE (mGRE)
+ Next-Hop Resolution Protocol (NHRP)
+ Dynamic Routing Protocol (EIGRP, RIP, OSPF, BGP…) (optional)
+ Dynamic IPsec encryption (optional)
+ Cisco Express Forwarding (CEF)
IPsec is optional not required
C and D;
although not often the case, DMVPN can actually be setup without IPSec.
mGRE and NHRP however are mandatory components.
Thanks.
The explanation shows 3 answers, but the question asks for 2. I guess the more accurate answers are A nd D.