Home » Cisco » 300-101 » Which two DHCPv6 messages will appear in the sniffer logs?
An engineer is using a network sniffer to troubleshoot DHCPv6 between a router and hosts on the LAN with the following configuration:
Interface Ethernet0
ipv6 dhcp server DHCPSERVERPOOL rapid-commit
Which two DHCPv6 messages will appear in the sniffer logs? (Choose two)
A. SOLICIT
B. ADVERTISE
C. REQUEST
D. ACKNOWLEDGE
E. RENEW
F. REBIND
G. REPLY
Correct Answer: AG
Explanation/Reference:
See https://en.wikipedia.org/wiki/DHCPv6 he Rapid Commit option is used to indicate the use of the twomessage exchange for address assignment. The code for the Rapid
Commit option is 80. The format of the option is:
Code Len
+—–+—–+
| 80 | 0 |
+—–+—–+
A client MUST include this option in a DHCPDISCOVER message if the client is prepared to perform the DHCPDISCOVER-DHCPACK message exchange described earlier.
A server MUST include this option in a DHCPACK message sent in a response to a DHCPDISCOVER message when completing the DHCPDISCOVER-DHCPACK message exchange.
http://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/enterprise-ipv6-solution/whitepaper_c11-689821.html
Rapid Commit
The DHCPv6 client can obtain configuration parameters from a server either through a rapid two-message exchange (solicit, reply) or through a normal four-message exchange (solicit, advertise, request, reply). By default, the four-message exchange is used. When the rapid-commit option is enabled by both client and server, the two-message exchange is used.
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/configuration/15-2mt/ipv6-15-2mt-book/ip6-dhcp.html