With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
swPimCandidateRPGroupMask
Switch Pim Candidate RP Group Mask
1.3.6.1.4.1.171.12.52.3.2.4.1.2
The multicast group address mask which, when combined with pimCandidateRPGroupMask, identifies a group prefix for which the local router will advertise itself as a Candidate-RP.
Back to PIM-SM-MIB MIB page.
IPHost Network monitor allows you to monitor swPimCandidateRPGroupMask on D-Link device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring D-Link switches right now.