Final answer:
To test and troubleshoot IPv6 connectivity on a Cisco network device, you should use the 'ping' and 'traceroute' commands. They help determine the reachability of an IPv6 address and the path packets take to reach their destination, respectively.
Step-by-step explanation:
The two commands that can be used on a Cisco network device to test and troubleshoot IPv6 connectivity are: ping and traceroute. The ping command is used to send ICMPv6 Echo Request messages to test the reachability of an IPv6 host. The command syntax is ping ipv6 [destination-address], where you replace [destination-address] with the actual IPv6 address you are trying to reach. Traceroute, on the other hand, is used to identify the path that packets take to reach their destination by sending ICMPv6 messages. The command for traceroute is traceroute ipv6 [destination-address].
The commands show ipv6 interface and show ipv6 route are used for viewing IPv6 interface status and the IPv6 routing table, respectively, rather than for direct connectivity testing. The command ipconfig is not used on Cisco devices, but on Windows operating systems to display all current TCP/IP network configuration values.