Server authenticate the received information request with HMAC MD5 algorithm when received message contains the Authentication option tlv .Realms are container for authentication information. For the Authentication key id is required. Keys are assigned to clients. This table is used to create the Realm Row and the fsDhcp6SrvRealmIndex index is also used by the fsDhcp6SrvAuthClntTable. Following is an example of a server authentication hierarchy: realm testrealm01.private.com { key 1 TESTREALMKEY01 key 2 TESTREALMKEY02 } realm testrealm02.private.com { key 1 TESTREALMKEY01 }