Which command sets the key-length for the IPv6 SeND protocol?

A.
ipv6 nd inspection

B.
ipv6 nd ra-interval

C.
ipv6 nd prefix

D.
ipv6 nd secured

E.
ipv6 nd ns-interval

Explanation:
ipv6 nd secured key-length [[minimum | maximum] v alue
Example:Router(config)# ipv6 nd secured key-length minimum 512
http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/configuration/15-
2mt/ipv6-15-2mt-book/ip6-first-hop-security.html