With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
swDHCPLocalRelayState
Switch DHCP Local Relay State
1.3.6.1.4.1.171.12.42.4.2.1.2
This object indicates the state of the DHCP relay function of the specified VLAN.
Back to DHCP-RELAY-MGMT-MIB MIB page.
IPHost Network monitor allows you to monitor swDHCPLocalRelayState 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 routers right now.