This paper presents a modified standard for Internet Security Associations and Key Management Protocol (ISAKMP) Domain of Interpretation (DOI) for group key management to support secure group communications. The Group Domain of Interpretation (GDOI) manages group security associations, which are used by IPSec (Internet Protocol Security) and other potential data security protocols running at the IP or application layers. These security associations protect one or more key-encrypting keys, traffic-encrypting keys and data shared by group members. In this paper few inadequacies like lack of group identification, lack in unique Source authentication of ESP (Encapsulated Security Payload) and bottle neck in the Group Controller Key Server (GCKS) are addressed and modifications are suggested in order to make GDOI a more secure protocol. The experimental results also prove the above claim.