Answer:
The two router configuration lines that should be verfifed to ensure that stateless DHCPV6 service is properly configured are:
R1# configure terminal and R1# show ipv6 dhcp pool
Explanation:
As the router has been configured by network administrator for stateless DHCPV6 operations, then the users are supposed to be receiving DNS Server information. However, if the situation remains as stated in the question then the router can be checked for configuration issues by verifying the lines stated above .