With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
swL3RelayDnsSecondaryServer
Switch L3 Relay Dns Secondary Server
1.3.6.1.4.1.171.11.70.5.3.3.2.3
This object indicates the address of the secondary DNS server.
Back to DES3552-SWL3MGMT-MIB MIB page.
IPHost Network monitor allows you to monitor swL3RelayDnsSecondaryServer 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.