which router is acting as a group member?

CORRECT TEXT

Which router is acting as the key server and which router is acting as a group member? (Choose two)

Answer: R2# show crypto gdoi ks -or- R2# show crypto gdoi ks members -or- R1# show ip

Explanation:
interface brief

NB: it is assumed that only R1 is a member router and ISP is not a member
R1#show crypto gdoi ks
Total group members registered to this box: 0

All commands can be referenced here
http://www.cisco.com/en/US/docs/ios/security/command/reference/sec_s3.html#wp1159252