With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
swDHCPServerPoolLeaseHour
Switch DHCP Server Pool Lease Hour
1.3.6.1.4.1.171.12.38.3.2.1.1.8
The hour of the lease.
Back to DHCP-Server-MIB MIB page.
IPHost Network monitor allows you to monitor swDHCPServerPoolLeaseHour 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.